Not Enough Disk Space to Install High Sierra?

Just move the installation file to flash drive.

It's on Application folder. Just drag it to flash drive.

Just make sure that it have ntfs or hfs or Mac OS Extended format. FAT will not be able to copy it since it's more than 4GB.

Adding a Comma between Author and Year on Biblatex?

Simple, just add this line at preamble.

\usepackage[style=authoryear]{biblatex}
\renewcommand{\nameyeardelim}{\addcomma\addspace}

.

Change '1st Edition' into 'Edisi 1' in LaTeX.

My LaTeX document on Indonesian language has had proper citation style on bibliography using biblatex; the ''disitasi pada halaman" instead of "cited on page".

Of course the new problem arise. Like this.

Look that I have "1st Edition" or "2nd Edition" here and there. It supposed to have "Edisi 1" or "Edisi 2" form respectively.

Okay, thats not new problem (it's the kind of the last minute problem before the show, :D ).

So I add this line at the preamble.

\DefineBibliographyStrings{english}{
 backrefpage = {disitasi pada halaman},
 backrefpages = {disitasi pada halaman-halaman},
 edition = {edisi},
 in = {dalam},
 and = {dan},
 urlseen = {diakses pada}
}
\DeclareFieldFormat{edition}{\ifinteger{#1}{\bibstring{edition}~\mkbibordedition{#1}}{#1\isdot}}

.

Looks good.

Change the "Cited on Page" Strings in LaTeX.

I have LaTeX document written in Indonesian and it's nice and yada yada. The minuscule problem is the bibliography. I used biblatex and it look like this.

The problem is "cited on page" and "cited on pages" string. It's supposed to be "disitasi pada halaman" and "disitasi pada halaman-halaman".

What I need is add this lines to preamble.

\DefineBibliographyStrings{english}{
 backrefpage={disitasi pada halaman},
 backrefpages={disitasi pada halaman-halaman}
}

And I got this, :)

All was well, :)

HyperRef and Bookmark Combo in LaTeX.

I use this preamble in order to show bookmarks on PDF generated from my .tex file.

This way, we could navigate through part, chapter, section and subsection (depending on our depth setting) using table of content sidebar of PDF reader.

code

\usepackage{hyperref}
\hypersetup{hidelinks,backref=true,pagebackref=true,hyperindex=true,colorlinks=false,breaklinks=true,urlcolor= ocre,bookmarks=true,bookmarksopen=true,bookmarksdepth=3,pdftitle={Title},pdfauthor={Author}}
\usepackage{bookmark}
\bookmarksetup{
open,
numbered,
addtohook={%
\ifnum\bookmarkget{level}=0 % chapter
\bookmarksetup{bold}%
\fi
\ifnum\bookmarkget{level}=-1 % part
\bookmarksetup{color=ocre,bold}%
\fi
}
}

.

BibLaTex Problem

Have you had this error?

$ biber main.aux
INFO - This is Biber 2.1
INFO - Logfile is 'main.aux.blg'
ERROR - Cannot find control file 'main.aux.bcf'! - did you pass the "backend=biber" option to BibLaTeX?
INFO - ERRORS: 1
Nugrohos-MacBook-Air:tesBibTex nugroho$ 

Me too.

The solution is simple, make sure the command is

$biber main

and not

$biber main.aux

Using Kivy on MacOS

Here's my first kivy program after a while.

Adding Piezo and Replace Tune O Matic on ES175 Replica.

Why? I want acoustic electric package in one guitar. In order to install Fishman piezo, I need to replace Tune O Matic with regular acoustic bridge saddle.

Is it success? Uh, oh, maybe.

What about sound after mod? It's nearly acceptable.

Nearly? Err, there's fret bussing, the action of the mod with acoustic saddle is too low.

Just that? There's intonation problem too, I couldn't set individual string length on the bridge.

Are you crazy? Yup.

Are you happy now? Not yet.

Guitar Intonation.

Have you tune your guitar using clip-on tuner and it's perfectly in tune for all open strings, but it getting horribly out of tune at high fret. Yup, that's intonation problem striking at you.

What's guitar intonation? Well, on traditional style guitar, with straight frets, the fret placement is based on a string or based on 'standard'  measurement. The problem with this placement is while it's fine with 1st string, it doesn't sound right with 2nd string (b) or 3rd (G). Of course it's like Heisenberg Uncertainty Principle, if we make it work on G-string, it will sound wrong on high-e string.

Can it be solved? Some people using 'true temperament' system on their fretboard. The fret in this system is not straight but have a certain shape in order to get the strings perfectly in tune. Of course different string gauge will need different fret shape so one guitar will stuck on one type of string. (We might use another string, but it will out of tune, maybe worse than standard straight frets).

Okay, it's not generally practical. Is there another way?

Playing with Memo in Delphi

I change the font in memo (tMemo) into courier. With this change, it's easy to do string manipulation with old Pascal style.

Below, I create small program with read input from edit into n variable. The input can only contain number 1 to 9.

The output is displayed on Memo. It's just number 123456789 (yeah, it has type string, but its number).

It's that all? No. The number's forming a 'cross' centered on number specified in edit. :)

Palindrom Checker

This simple program is using an edit as input, a button to trigger processing and a memo for output.

I used edit.text as s value and then reverse its value using for command and saved to rs variable.

We compared s and rs to determine that s is palindrom or not.



Here's the code

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Memo1: TMemo;
    Button1: TButton;
    procedure proses;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
procedure tform1.proses;
var s,rs:string;
  i:integer;
  palindrom:boolean;
begin
  memo1.Text:='';
  palindrom:=true;
  s:=edit1.Text;
  for i:=length(s) downto 1 do begin
    rs:=rs+s[i];
  end;
  for i:=1 to length(s) do begin
    if s[i]<>rs[i] then begin
      palindrom:=false;
      break;
    end;
  end;
  memo1.Lines.Append(s);
  memo1.Lines.Append(rs);
  if palindrom=true then
    memo1.Lines.Append('is palindrom')
      else
        memo1.Lines.Append('is not palindrom');

end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  memo1.Text:='';
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  proses;
end;

end.

.

Walking Star in Delphi's Stringgrid.

This code moves the star from cell to cell on string grid.

I use variable s, an array of string type variable.

For delay, or controlling the speed, I use application.processmessages and sleep() combo command.

This code fills cell with blank (space) value that corresponds with s, except one cell. This one cell then "moves" to the right, into the cell next to it.

For this purpose I declare two integer type variable, sx and sy. This variable add itself by one every step. Based on this two variable, the cell that should be filled with star is decided.

Digit Word.

A digit word is a word where, after possibly removing some letters, you are left with one of the single digits:
ONE, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT or NINE.
For example:
• BOUNCE and ANNOUNCE are digit words, since they contain the digit ONE.
• ENCODE is not a digit word, even though it contains an O, N and E, since they are not in order.
 

Here's my code on Delphi

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Button1: TButton;
    Memo1: TMemo;
    procedure proses;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  digit,cdigit:array[1..9] of string;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  memo1.Text:='';
  digit[1]:='one';
  digit[2]:='two';
  digit[3]:='three';
  digit[4]:='four';
  digit[5]:='five';
  digit[6]:='six';
  digit[7]:='seven';
  digit[8]:='eight';
  digit[9]:='nine';
end;

procedure tform1.proses;
var s:string;
    i,j,k,n:integer;
    c:array[1..9]of integer;
    ck:array[1..9]of boolean;
begin
  memo1.Text:='';
  s:=edit1.Text;
  memo1.Lines.Append(s);
  memo1.Lines.Append('');
  n:=length(s);
  for i:=1 to 9 do begin
    cdigit[i]:='';
    c[i]:=1;
    ck[i]:=true;
  end;

  //looking for char
  for i:=1 to 9 do begin
    for j:=1 to length(digit[i]) do begin
      if ck[i]=true then begin
       ck[i]:=false;
       for k:=c[i] to n  do begin
        if s[k]=digit[i][j] then begin
          ck[i]:=true;
          cdigit[i]:=cdigit[i]+s[k];
          c[i]:=c[i]+1;
          break;
        end;
       end;
      end;
    end;
  end;
  //compare
  for i:=1 to 9 do begin
    memo1.Lines.Append(cdigit[i]);
  end;

end;
procedure TForm1.Button1Click(Sender: TObject);
begin
  proses;
end;

end.

.

Animation using Matplotlib

Suppossed we want to animate our plot, say f(x) = (x-c)^(2) to see the effect of various c value, we could do it in Python using Matplotlib module.

As we could see at the code below that the animation part is in

ani =  animation.FuncAnimation(fig, animate, np.arange(-10,10), interval =  25, blit=False)

What about our own def? We could call it inside animate and use variable i (defined in ani, the np.arange(-10,10) part) to whatever treatment on our self define function f(x). In this case, I use i as c parameter value. I like the result, :)

What About Unbounded End?

Yeah, what about it? The previous code have the both end bounded.

If we want a free/unbound end, we could set the condition at the with this properties (or we could choose whatever we like)

dy/dx=0

So we will have

y[1]-y[0]=0
y[0] = y[1]

if we want both free ends, we could set the other end as well

y[n] = y[n-1]

So, we just have to modify the original just a bit.

Beware though, with both ends free, we could lost the strings, :)

Waves Equation Animation in Python

I use matplotlib module to do the animation.

The main code is in def waves(y0,y1,cb) that use finite difference that solved initial value problem and boundary value problem simultaneously.    

code
from pylab import *
import matplotlib.animation as animation

fig,ax = subplots()

def waves(y0,y1,cb):
    y2 = y0
    for i in range(1,len(y0)-1):
        y2[i] = 2*y1[i]-y0[i]+cb*(y1[i+1]-2*y1[i]+y1[i-1])
    return y2

x   = linspace(0.,1.,20)
dx  = 1./(len(x))
y0  = sin(2*pi*x)
vy0 = 12.

b   = 1./32.  #dt2/dx2
dt  = sqrt(b*dx*dx)
print dt

c   = 1.

cb  = c*b

y1  = y0 + vy0*dt

print y0
print y1

line,   = ax.plot(x,y0)
def animate(i):
    global y0,y1,cb
    y2  = waves(y0,y1,cb)
    y0  = y1
    y1  = y2
    line.set_ydata(y0)
    return line,


#plot (x,y0)

ani =  animation.FuncAnimation(fig, animate, np.arange(1,200), interval =  25, blit=False)

grid(True)
ylim(-10,10)
show()

.

Gauss Jordan in Python.

Yeah, it's basically Gauss elimination (or we could call it Gauss Naif :) ) but with slight modification at the end.

So, instead using back substitutions after zeroing the lower triangle, we straight on and zeroing upper triangle as well. As addition, we could normalize the diagonal elements so we have identity matrice.

And all is well, :)

"Auto" Gauss Naif in Delphi.

After do this in Python, now it's time to bring it back to Delphi, where all of this is started, :)


The heart of code lay on this one

procedure tform1.gauss;
var i,j,k:integer; temp:real;
begin
  for i:=1 to 9 do begin
    for j:= 1 to i do begin
      if t[i,j]<>0 then begin
        temp:=t[i,j];
        for k:= 1 to 10 do begin
          if i=j then
            t[j,k]:=t[j,k]/temp
              else t[i,k]:=t[i,k]/temp - t[j,k];
        end;
      end;
    end;
  end;
  //back subtitution
  for i:=9 downto 1 do begin
    x[i]:=t[i,10];
    for j:=9  downto i do begin
      if i<>j then
        x[i]:=x[i]-x[j]*t[i,j];
    end;
  end;

You could say that it consists of zeroing lower tringle and normalizing the diagonal and then subtituting the value.

There's little failsafe code here, that is if we already have zero cell, don't proceed, or it will gave divided by zero error.

Gauss Naif in Python

Okay, we've done the manual one, how about automatize it?

It's actually just a matter of finding the pattern on that code and after we found the loop, we just have to well... loop it, :)

Manual Gauss Jordan in Python.

What if we didn't do back substitution on Gauss Naif method but eliminate the rest instead? Nah, we get the Gauss Jordan here.

The idea is after we do operation to make the  lower-triangle have zero value,  we continue the operation until all the component in the upper-triangle have zero value too, and the diagonal have value of one.

Basically, the matrix becomes identity matrix. This way, we didn't need subtitution at all since all variables already has the exact value on the right side, :)

Manual Gauss Naif Elimination using Python

How about some manual matrix using manual Gauss just like always, but in Python? Okay, here it is.

I use tuple, I think it's just the same as array for this purpose.

I created matrix a with random value.  It's like linear equation system; three unknown variables with three equation. The purpose of this code is to find x1, x2 and x3.

Oh, in this case, its x0, x1 and x2, :)

That's Not Fair!

Maybe that's something come to our mind when we read this code. Yeah, that's forward dfference. It's designed to get the difference value using the point we calculate and the next one. That means the value will "lopsided" by nature, :)

Searching Multiple Roots Numerically.

This Python code only works with function that crossing x-axis.

The idea is we started from x=0 and walking to the positive direction and evaluating f(x) as we walk.

If there's change of the sign of f(x) from + to -, or vice versa, there must be a root in that area.

We began to surround it to find the-x that correspond to f(x)=0. That x value is the root.

After the root is found, we began to walk along x-axis again until found any sign change of f(x), or until x limit set on code.

Manual Gauss Elimination on 3x3 Matrices in Delphi

I use this code in order to find its pattern.

Yes, there is many Gauss code out there. I plan to write it on next post about it. The dynamic Gauss Elimination code that could be implemented to any size of matrices.

But for now, let just settle on this.

https://youtu.be/csiFpdsrzzQ

Tadaa...

Again, :)

Lagrange Polynomial Interpolation on Python.

It's a whole a lot easier than Newton's divided differences interpolation polynomial, because there is no divided difference part that need a recursive function.

Dewa.

Tentang religi, sepertinya @pitoyoamrih memang sangat berhati-hati sekali. Beliau menempatkan setting cerita bukan di dunia nyata kita (yang sudah penuh kontroversi religi), namun di dunia tersendiri yang bernama dunia wayang,  :)

Pun demikian, toh dewa-dewa di dunia wayang @pitoyoamrih tidak bertindak sebagai Tuhan, namun sebagai makhluk dengan tugas dan kemampuan khusus.

 

Bahkan di banyak cerita, para dewa ini cenderung  bertindak seperti oknum pejabat yang korup dan/atau sewenang-wenang sehingga perlu dilabrak oleh rakyatnya, :)

Sukati dan Penyukilan.

Akhirnya saya tahu yang ini. Lagi-lagi @PitoyoAmrih menambal lubang di kamus wayang saya. :) 

Kali ini tentang nama alias.

Saya sudah cukup akrab dengan nama alternatif di dunia wayang. Bahkan dengan beberapa gagrak yang berbeda.

Permadi, Pinten, Tangsen, Yayi Suni, kakang Suman, Bawor, Jaka Pitana, Suyudana, Jaladara, Kakrasana,...

Tak Terduga dan Menyenangkan.

Masih mbulet di buku @PitoyoAmrih, dengan gaya cerita beliau yang seperti orang ngobrol santai diantara teman.

Awalnya, saat memegang buku "Pertempuran Dua Pemanah. Arjuna-Karna" untuk pertama kali, saya sudah penuh dengan antisipasi bahwa ini bukan hanya tentang pertempuran dua orang itu.

Seperti di "Wisanggeni Membakar Api" atau "Antareja dan Antasena", saya menduga bahwa Pitoyo Amrih pasti akan menceritakan masa kecil Karna dan Permadi, yang memang dilakukan oleh beliau.

Namun ada tokoh "utama" lagi yang menyedot fokus saya yang disuguhkan beliau, ada pemanah lain. Adalah Ekalaya, Raden Bambang Ekalaya, raja Paranggelung, yang ternyata juga pemanah hebat. Yang sebelumnya hanya saya kenal sepintas lalu sebagai raja bergelar Prabu Palgunadi. Itupun, di otak saya, selalu tak lepas dari nama lain yang harus selalu hadir di imajinasi saya, meskipun saya tak tahu ada apa dengan dua nama tersebut. Nama itu adalah Palguna-Palgunadi.

Hal lain yang saya perhatikan adalah gaya bercerita Pitoyo Amrih di novel ini. Tadi sudah saya sebut bahwa beliau bercerita seperti ngobrol santai diantara teman. Ngobrol santai, tak ada jadwal, tak ada target, tapi tetap bikin nyaman. Bukankah itu tujuan santai diantara sahabat?

Ngobrol santai bagaimana? Yeah, saat kita ngobrol, saat kita sedang bicara tentang suatu topik, adakalanya topik itu merembet ke topik yang lain, yang juga merembet ke topik yang lainnya lagi, dan lainnya lagi, yang kemudian dengan santainya, mungkin sambil menyeruput kopi hangat yang tinggal separuh, kembali ke topik awal dengan mulus tanpa terkesan dipaksakan.

Hal itu terjadi di buku ini, betapa cerita masa kecil Karna tiba-tiba bergeser ke sayembara Kunti, geger Kangsadewa, dan kembali ke Karna lagi.

Saat ngobrol, kadangkala urutan kronologis juga sering tak beraturan. Kita bicara tentang kejadian hari ini yang merupakan akibat dari kejadian dua minggu yang lalu, yang direncanakan seminggu sebelum itu, berakibat dua minggu kemudian, dan akan kita lihat apakah besok ada akibat dari kejadian yang sekarang.

Hal yang sama saya kenali di buku ini saat tiba di bagian Ekalaya, berawal dari Ekalaya yang sudah lusuh, mundur ke Ekalaya saat masih di istana, maju sedikit ke bagian Ekalaya yang ditolak Durna, maju lagi, dan lagi. 

Apakah membingungkan? Dari sisi cerita, ini justru menarik karena kita tahu sebuah akibat dulu, sehingga penasaran apa sebabnya, yang kemudian dijawab dengan elegant oleh Pitoyo Amrih. Sehingga jalan cerita jadi menarik, misteri atau rasa penasaran selalu jadi bahan bakar cerita yang menarik.

Akan lain halnya misal bagian Bambang Ekalaya diceritakan runtut secara kronologis, tak akan menarik karena kita akan tahu hasil akhirnya, atau mungkin malah tidak tahu sama sekali mau mengarah ke mana. Pitoyo Amrih tahu cara membuat cerita menjadi menarik. :)

Unexpected and Enjoyable.

It's still around @PitoyoAmrih book, with his story style that is like people chatting casually among friends.

Initially, when holding the book "Pertempuran 2 Pemanah. Arjuna-Karna", "Battle of the Two Archers. Arjuna-Karna" for the first time, I was full of anticipation that this was not just about the battle of the two people.

As in "Wisanggeni Membakar Api" or "Antareja and Antasena", I suspect that Pitoyo Amrih will surely tell about Karna and Permadi's childhood, which he did.

But there is another "main" character who appeared in the focus. There are other archers. It was Ekalaya, Raden Bambang Ekalaya, king of Paranggelung, who was also a great archer. Previously, I only knew at a glance as a king, Prabu Palgunadi. And even then, in my brain, it always can't be separated from other names that must always be present in my imagination, even though I don't know what/who the two names are. The name is Palguna-Palgunadi.

Another thing I noticed was the storytelling style of Pitoyo Amrih in this novel. I mentioned earlier that he told stories like casual chatting between friends. Chat casually, no schedule, no targets, but still comfortable. Isn't that a relaxed goal while chatting among friends?

Chat casually what? Yeah, when we talk, when we're talking about a topic, sometimes the topic spreads to other topics, which also spread to another topics, and more, which then casually, maybe while sipping a half cup of warm coffee, return to the original topic smoothly without being forced.

This happened in this book, how the story of  Karna's childhood suddenly shifted to the Kunti contest, commotion Kangsadewa, and returned to Karna again.

When we're chatting, sometimes the chronological order is also often irregular. We are talking about what happened today which was the result of the incident two weeks ago, which was planned a week before that, resulting in two weeks later, and we will see if tomorrow there will be a result of what is happening now.

The same thing I recognized in this book when I arrived in the part of Ekalaya, started from Ekalaya who was already worn out, retreated to Ekalaya while still in the palace, advanced slightly to the Ekalaya section which was rejected by Durna, advanced again, and again.

Is it confusing? In terms of the story, this is actually interesting because we know a result first, so we wondered why, which was then answered elegantly by Pitoyo Amrih. So that the storyline becomes interesting, mystery or curiosity is always became a fuel for an interesting story.

It will be different, for example, if Bambang Ekalaya's part is told in chronological order, it will not be interesting because we will know the end result, or maybe we don't know where it'll go at all. Pitoyo Amrih knows how to make stories interesting. :)

Differentiation

We may already knew that on computational physic,  differentiation is used in Euler method to compute integration, or used in finite different method.

How about slope of the function? How do we use differentiation to differentiate a function?

If we have y = f(x), we will have slope value on, say, (x0 , f(x(0)) by differentiate it.

m = dy/dx = df(x)/dx.

For slope on x0, just compute it.

We could plot the linear function that have form

y = m x + c

Creating (And Editing) Movie using iPhone, Macbook Air and Final Cut Pro.

I "clone" myself so I could play music in format trio, :)



.

What we need?

Of course:

• A camera, I use iPhone Camera, I have iPad Pro but...
• A tripod, I use iPhone because my iPad couldn't be mounted on this.  
• A Mac, Final Cut Pro only run on Mac, I use Macbook Air.
• ehm, keyboard, guitar, bass guitar, whatever.
• (optional), sound recording device, my iPad have decent video-sound, but sadly my iPhone isn't (maybe defect product), so I use Behringer Xenyx with usb interface and connect it to my iPhone using usb to lightning adapter.
• a metronome, since I don't use iPad to recording, I play metronome apps an it, :) .

Okay then.

To make a video, first we have to make a video, :)

I, mean using camera. Here, the tripod is important. To be able to make a "triplet" on the same room, we have to record it sequentially using the same camera position.

So, I start with acoustic nylon guitar part from start to end, and immediately switch to bass guitar to play the bass part, and finally the keyboard part.

Keep in mind that we have to play at the different place at the room and avoid abrupt motion that could overlap each other. 

Create a virtual zone for guitarist, bassist and keyboardist and 'they' have to play the instrument on their own zone.

I have to take this session twice because the first one didn't produce audio. It turn out that I have to tighten usb cable between iPhone and Xenyx (which I should do at the beginning, :) )    

Gibbous Moon

Baru ingat (atau sadar) tadi pagi saat ngantar Alfa Beta ke Budhe dan lihat bulan benjol di atas gunung.

Pantas semalam Beta bangun tengah malam, ndak bisa tidur lagi, trus minta pintu kamar ditutup sesaat setelah fokus ke pintu.

Dia biasanya saat mau tidur selalu minta pintu kamar dibuka lebar-lebar, kecuali tadi malam, tengah malam, :)

Lah, tapi kemarin kukannya  jumat malam sabtu, dan di Indonesia hantu memiliki jadwal standart untuk muncul di kamis malam jumat dan tak ada urusan sama bentuk bulan.

Yeah, seperti kita yang ndak lagi hanya makan nasi jagung atau tiwul, tetapi juga suka spaghetti dan pizza, kemungkinan hantu-hantu Indonesia juga berkembang. 

Mereka mungkin selalu update informasi bahwa di luaran sana ada waktu keluar hantu yang beda, bukannya "Malam Jumat Kliwon" tetapi "Friday Night". Ada juga pesta hantu tahunan saat  hari jumat bertepatan dengan tanggal 13, yang di daerah jawa mungkin setara dengan tanggal Satu Suro.

Mungkin mereka juga berhubungan via media sosial dengan hantu-hantu luar negeri yang sharing bahwa ada komunitas hantu Eropa yang muncul saat bulan berbentuk benjol.

Dengan demikian, tidaklah mengherankan jika saat ini hantu-hantu bisa muncul setiap saat, karena mereka mungkin juga sudah bosen ratusan atau ribuan tahun melakukan hal yang sama terus menerus, :)

#edisiError

(Saya punya pengalaman sendiri saat saya masih suka tidur di luar rumah, di halaman lantai dua sambil lihat bulan dan bintang hampir tiap malam. Pada suatu malam, dini hari, bulan benjol tepat di atas kepala, tiba-tiba saya dipijit oleh seseorang (atau entah apa itu yang berbentuk orang) dengan fisik seperti nenek saya yang saya panggil "mak kecil" [saya punya tiga nenek resmi saat itu, :) ], nah nenek ini tidak mungkin ke tempat saya saat itu berbaring, lha wong rumahnya jauh. Setelah beberapa hari kemudian saya klarifikasi, ternyata dengan enteng semua sepakat bahwa itu bukan nenek saya [bahkan 'mak kecil' pun setuju], namun ibu dari nenek saya yang sudah meninggal [bahakan saat saya belum lahir] karena deskripsi fisiknya benar-benar tepat dan beliau memang punya style pijat yang unik. Wah... )

Numeric Integration using Python and Pylab

Pylab is Python module that contain NumPy and MatPlotlib.

Let f(x) = x^2 and we want to integrate it from 0 to 1.

Numerically we could use square method or trapezoidal (which is almost better).

Masa Kecil

Salah satu detil dari @pitoyoamrih yang saya suka adalah cerita tentang masa kecil seorang tokoh wayang. 

Kita tahu cerita lengkap tentang masa kecil tokoh wayang jarang ada di pakem utama. Hanya beberapa yang terkenal seperti Gatotkaca dan Wisanggeni, itupun dalam lakon  carangan.

Dengan kenyataan seperti itu (atau saya yang memang tidak tahu secara tuntas pakem utama pewayangan), buku-buku Pitoyo Amrih ini menjadi semacam hiburan yang menyegarkan. 

Tentang masa kecil Karna bersama Adirata. Deskripsi watak Karna yang ambisius, nakal dan cenderung jahat kepada orang tua angkatnya menjadi pengantar yang tepat sebagai latar belakang masa dewasanya.

Permadi kecil, sebelum diusir dari istana, yang cuek cenderung sombong dan manja, tak mau membereskan busur dan tempat anak panah.

Narayana dan Kakrasana kecil di Widarakandang yang diasuh Demang Antagopa dan Nyai Sagopi.

Masa kecil para kurawa dijelaskan dengan rapi, tentang Destarata dan Gendari yang tidak pernah memperhatikan anaknya sama sekali, dan seratus saudara seumur yang tak terurus sehingga menjadikan pengantar kelakuan Kurawa saat sudah dewasa.

Masa kecil Wisanggeni mungkin sudah banyak yang tahu karena ada lakon Lahirnya Wisanggeni.

Nah saya suka cerita detil versi Pitoyo Amrih tentang masa kecil Antareja dan Antasena. 

Childhood

One of the details of @pitoyoamrih that I like is the story of the childhood of a puppet character.

We know the full story about the childhood of puppet characters is rarely in the main Pakem. Only a few are famous like Gatotkaca and Wisanggeni, and even then in the Carangan (side story).

With such a reality (or it's just me, who  don't really know the complete Pakem of Wayang ), Pitoyo Amrih's books become a kind of refreshing entertainment.

About Karna's childhood with Adirata. Descriptions of Karna's ambitious, naughty and evil tendencies to her adoptive parents became the right introduction to her adult background.

Young Permadi, before being expelled from the palace, the ignorant tended to be arrogant and spoiled, not wanting to clear the bow and place the arrow.

Narayana and small Kakrasana in Widarakandang who are raised by Demang Antagopa and Nyai Sagopi.

The kurawa's childhood is neatly explained, about Destarata and Gendari who never pay attention to their children at all, and a hundred brothers during their unkempt years, making strong background of Kurawa's behavior as adults.

Wisanggeni's childhood may have been known because there was a play about the birth of Wisanggeni.

Now I like the detailed version of Pitoyo Amrih's version of Antareja's and Antasena's childhood.

Delphi.

Still using Delphi?

Yup, it teach me about programming discipline, :)

Flappy Bird Like in Delphi

Remember the infamous Flappy Bird? Yup, I will create the program based on that algorithm.

Newton Polynomial in Python

I wrote code for this in Delphi. This time I want to rewrite it in Python based on this wiki.

I use this set of data point
(0,0)
(1,1)
(2,4)
(4,16)
(5,25)

and I use xc=3 for the test data.

It's obvious that these sets of data points have quadratic form and f(xc) must have value of 9.

The heart of code lay on this

def n(j,xc,x):
    n = 1
    for i in arange(j):
        n *= (xc-x[i])

    return n
def a(j,l,x,y):
    if j==0:
        return y[0]
    elif j-l==1 :
        return (y[j]-y[l])/(x[j]-x[l])
    else:
        return (a(j,l+1,x,y)-a(j-1,l,x,y))/(x[j]-x[l])
        

def N(xc,x,y):
    N = 0
    for j in range(len(x)):
        N += a(j,0,x,y)*n(j,xc,x)
    
    return N

Look at the function a(j,l,x,y), that's recursive function to obtain Newton divided difference value.

the whole code is this

from pylab import *

def n(j,xc,x):
    n = 1
    for i in arange(j):
        n *= (xc-x[i])

    return n
def a(j,l,x,y):
    if j==0:
        return y[0]
    elif j-l==1 :
        return (y[j]-y[l])/(x[j]-x[l])
    else:
        return (a(j,l+1,x,y)-a(j-1,l,x,y))/(x[j]-x[l])
        

def N(xc,x,y):
    N = 0
    for j in range(len(x)):
        N += a(j,0,x,y)*n(j,xc,x)
    
    return N

x = []
y = []
#initial value
x.append(0)
x.append(1)
x.append(2)
x.append(4)
x.append(5)

y.append(0)
y.append(1)
y.append(4)
y.append(16)
y.append(25)

#for testing
xc = 3

yc = N(xc,x,y)

print ''
print xc, yc
#plot
t = linspace(-7,7,100)
u = N(t,x,y)
plot(t,u)
grid(True)
show()

.


here's the graphics

with another sets of data points, I have another result
(0,0)
(1,1)
(2,4)
(4,16)
(5,25)

Disorientasi

Kadang bingung sedang membaca buku @PitoyoAmrih yang mana, saking konsistennya. Banyak cerita yang ada di buku satu, menyisip di buku lainnya. Seakan empat atau lebih buku itu sebenarnya cuma satu buku yang dijilid bukan berdasarkan urutan, namun berdasarkan tema.

Saat membaca "Antareja dan Antasena", tiba-tiba serasa baca "Wisanggeni Membakar Api" saat tiba di bagian Antasena menjadi jagung.

Juga saat membaca "Pertempuran Dua Pemanah: Arjuna-Karna" serasa membaca sisipan dari (atau malah babon) dari "Kebaikan Kurawa".

Apakah itu berarti jelek? Tidak sama sekali. Ini berarti penulis memiliki satu plot besar yang dicurahkan di berbagai buku.



Eh, tentu saja memang ada plot besar bernama pakem di pewayangan,  :).

Hal yang menarik di sini, dengan berpegang pada plot besar, buku-buku Pitoyo Amrih memiliki konsistensi yang tinggi. Baca buku yang manapun tidak akan mengalami kebingungan tentang mana yang benar karena yang diceritakan bersumber dari hal yang sama. Namun ada juga detil-detil kecil yang menarik yang memang tidak ada di pakem atau (plot besar milik Pitaya Amrih sendiri), detil-detil ini membuat cerita menjadi menyenangkan karena tidak menjadi kaku karena pakem.

Banyak buku yang menjadi  kaku karena terlalu ikut pakem, atau buku yang terlalu aneh karena tidak mempedulikan pakem sama sekali (jadinya pembaca malah mengernyit sambil mikir "Arjuna kok gini?", "Samba kok gitu?" dsb )

Ohya, saya belum baca semua buku Pitoyo Amrih, dalam proses, tetapi sudah pasti jadi pengagum  beliau, :)

Disorientation

Sometimes I confused about reading the book @PitoyoAmrih, because it's too consistent. Many stories in a book, are inserted in other books. As if four or more books were actually just one book bound not by sequence, but by theme.

When reading "Antareja and Antasena", suddenly I read "Wisanggeni Membakar" when I arrived in the Antasena-became-Corn section.

Also when reading the "Pertempuran Dua Pemanah: Arjuna-Karna" it seemed that I read the insertion from (or even the baboon) of "Kebaikan Kurawa".

Does that mean bad? Not at all. This means that the author has one large plot devoted to various books.

Uh, of course there is indeed a big plot called the Pakem (Standart Plot) in Shadow Puppet story, :).

The interesting thing here is, by holding on to the big plot, Pitoyo Amrih's books have high consistency. Read any of his books. We will not experience a confusion about what is right because the story is from the same source. But there are also interesting little details that are not in the Pakem. These details make the story fun because it does not become rigid because not strict into Pakem.

Many books are stiff because they are too gripping, or books are too strange because they don't care about The Pakem at all (so the reader frowns while thinking "Why is  Arjuna like this?", " Why is Samba like that?" Etc.)

Oh yeah, I haven't read all of Pitoyo Amrih's books, it's still in the process, but I have definitely become his admirer, :)

Newton Polinomial.

Here's code for Newton's divided differences interpolation polynomial (quite mouthful huh, :) ).

The purpose of this method is to create a function (polynomial) that passes through given set of data points.




I read data point from several edit box.

procedure TForm1.Button3Click(Sender: TObject);
var i:integer;
begin
  for i:=0 to n do begin
    x[i]:=strToFloat(kx[i].Text);
    y[i]:=strToFloat(ky[i].Text);
  end;
  xc:=strToFloat(kxc.Text);
  yc:=fn(xc);
  kyc.Text:=floatToStr(yc);
  gambarNewton;
end;

.
kx and ky is tEdit created when button1 is clicked

procedure TForm1.Button1Click(Sender: TObject);
var i:integer;
begin
  button2.Enabled:=true;
  button3.Enabled:=true;
  button4.Enabled:=true;
  button5.Enabled:=true;

  n:=strToInt(edit1.Text);
  kxc:=tEdit.Create(form1);       kyc:=tEdit.Create(form1);
  kxc.Parent:=form1;              kyc.Parent:=form1;
  kxc.Left:=36;                   kyc.Left:=72;
  kxc.Width:=36;                  kyc.Width:=36;
  kxc.Text:='0,5';

  for i:=0 to n do begin
    kx[i]:=tEdit.Create(form1);     ky[i]:=tEdit.Create(form1);
    kx[i].Parent:=form1;            ky[i].Parent:=form1;
    kx[i].Top:=36+36*i;             ky[i].Top:=36+36*i;
    kx[i].Left:=36;                 ky[i].Left:=72;
    kx[i].Width:=36;                ky[i].Width:=36;
    kx[i].Text:=intToStr(i);        ky[i].Text:=intToStr(i);
  end;
end;

xc is x coordinate where the corresponding y (yc) is obtained using Newton method by calling it

yc=fn(xc)

function tform1.fn(xs:real):real;
var i:integer;fs:real;
begin
  fs:=0;
  for i:=0 to n do begin
    fs:=fs+b(i,0)*c(xs,i);
  end;
  fn:=fs;
end;

the fn function call the two other function. The b function, a recursive contain divided difference like this

function tform1.b(i,j:integer):real;
begin
  if i=0 then b:=y[0]
    else if (i-j)=1 then
      b:=(y[i]-y[j])/(x[i]-x[j])
        else
          b:=(b(i,j+1)-b(i-1,j))/(x[i]-x[j]);
end;

and c function, a recursive function (or you could rewrite it using simple for command)

function tform1.c(xs:real;i:integer):real;
begin
  if i=0 then c:=1
    else c:=(xs-x[i-1])*c(xs,i-1);
end;

and finally, draw the data and the function on image1

fprocedure tform1.gambarNewton;
var i,x0,y0:integer;px,py:real;
begin
  x0:=image1.Width div 2;               y0:=image1.Height div 2;
  image1.Canvas.Brush.Color:=clLime;
  image1.Canvas.Rectangle(0,0,image1.Width,image1.Height);
  image1.Canvas.Brush.Color:=clWhite;
  image1.Canvas.Pen.Color:=clBlack;
  image1.Canvas.MoveTo(0,y0);           image1.Canvas.LineTo(image1.Width,y0);
  image1.Canvas.MoveTo(x0,0);           image1.Canvas.LineTo(x0,image1.Height);
  for i:=-300 to 300 do begin
    px:=i/skala;                          py:=skala*fn(px);
    image1.Canvas.Pixels[x0+i,y0-round(py)]:=clGreen;
  end;
  for i:=0 to n do begin
    px:=x0+skala*x[i];                        py:=y0-skala*y[i];
    image1.Canvas.Ellipse(round(px)-7,round(py)-7,round(px)+7,round(py)+7);
  end;
  px:=x0+skala*xc;                        py:=y0-skala*yc;
  image1.Canvas.Brush.Color:=clred;
  image1.Canvas.Ellipse(round(px)-7,round(py)-7,round(px)+7,round(py)+7);
  image1.Canvas.Brush.Color:=clwhite;
end;

Short Function.

Here's my implementation of function according to The Power of 10;

"Restrict functions to a single printed page."

As bonus, I didn't use global variable if possible. So if a function or procedure need a variable from others, it have to be passed using parameter on that function.

If we look at the code below, we know that it can be rewritten using a long single procedure or function. But according The Power of Ten, a function should be as short as possible so it could be printed in a single page.

So, instead one long multiple page function, I write/break it as several short-single-printed-page functions. :)

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    Edit3: TEdit;
    Edit4: TEdit;
    procedure proses;
    function konversi(a:real;c,d:char):string;
    function konversiC(a:real;d:char):string;
    function konversiF(a:real;d:char):string;
    function konversiR(a:real;d:char):string;
    function konversiK(a:real;d:char):string;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  proses;
end;

procedure tform1.proses;
var
  a:real;
  s,b:string;
  c,d:char;
begin
  a:=strToFloat(edit1.Text);
  s:=edit2.Text;
  c:=s[1];
  s:=edit4.Text;
  d:=s[1];
  b:=konversi(a,c,d);
  edit3.Text:=b;
end;

function tform1.konversi(a:real;c,d:char):string;
begin
  case c of
    'C':konversi:=konversiC(a,d);
    'F':konversi:=konversiF(a,d)
    'R':konversi:=konversiR(a,d)
    'K':konversi:=konversiK(a,d)
    else konversi:='error';
  end;
end;

function tform1.konversiC(a:real;d:char):string;
begin
  case d of
    'C':konversiC:=floatToStr(a);
    'F':konversiC:=floatToStr(a*9/5+32);
    'R':konversiC:=floatToStr(a*4/5);
    'K':konversiC:=floatToStr(a+273);
    else konversiC:='Error';
  end;
end;

function tform1.konversiF(a:real;d:char):string;
begin
  case d of
    'C':konversiF:=floatToStr((a-32)*5/9);
    'F':konversiF:=floatToStr(a);
    'R':konversiF:=floatToStr((a-32)*4/9);
    'K':konversiF:=floatToStr((a-32)*5/9+273);
    else konversiF:='Error';
  end;
end;

function tform1.konversiR(a:real;d:char):string;
begin
  case d of
    'C':konversiR:=floatToStr(a*5/4);
    'F':konversiR:=floatToStr(a*9/4+32);
    'R':konversiR:=floatToStr(a);
    'K':konversiR:=floatToStr(a*5/4+273);
    else konversiR:='Error';
  end;
end;

function tform1.konversiK(a:real;d:char):string;
begin
  case d of
    'C':konversiK:=floatToStr(a-273);
    'F':konversiK:=floatToStr((a-273)*9/5+32);
    'R':konversiK:=floatToStr((a-273)*4/5);
    'K':konversiK:=floatToStr(a);
    else konversiK:='Error';
  end;
end;

end.

.

Another Turtle in Circle

There's always another way to solve something.

So, I have another code for "Turtle in Circle" code, :)

In the script below, I use turtle position to determine if it's still inside circle or not. If it outside circle, instead of send it to zero position, I send it to random position inside circle.

import turtle
from random import uniform
import numpy as np

turtle.shape("turtle")
#turtle.speed(1)
x = 0
y = 0
rmax=40

for i in range (1,1000):
    a = uniform (-90,90) #angle
    turtle.left(a)
    d = uniform (-75,75) #distance
    x = turtle.xcor()+d*np.cos(a*np.pi/180)
    y = turtle.ycor()+d*np.sin(a*np.pi/180)
    r = np.sqrt(x*x+y*y)
    if r>rmax:
        turtle.setx(uniform(-rmax,rmax))
        turtle.sety(uniform(-rmax,rmax))
        x = 0
        y = 0
    else:
        turtle.forward(d)

turtle.exitonclick()



 

.

Turtle in Circle

I use previous code and improve it so the turtle could only move at certain circle area.

import turtle
from random import uniform
import numpy as np

turtle.shape("turtle")
#turtle.speed(1)
x = 0
y = 0

for i in range (1,1000):
    a = uniform (-90,90) #angle
    turtle.left(a)
    d = uniform (-75,75) #distance
    x += d*np.cos(np.pi*a/180)
    y += d*np.sin(np.pi*a/180)
    r = np.sqrt(x*x+y*y)
    if r>40:
        turtle.setx(0)
        turtle.sety(0)
        x = 0
        y = 0
    turtle.forward(d)

turtle.exitonclick()



 

.

Anti MainStream.

Saat booming sepatu roda, Alfa malah sibuk berlatih skateboard, :D .

Random Turtle Movement.

I use turtle module, the standard module, in Python.

The turtle movement has random direction (angle), and random distance (forward/backward).

import turtle
from random import uniform

turtle.shape("turtle")
turtle.speed(1)
for i in range (1,100):
    #random angle
    a = uniform (-90,90)
    turtle.left(a)
    #random move
    d = uniform (-100,100)
    turtle.forward(d)

turtle.exitonclick()



 

.

The Power of 10

Rules for Developing Safety-Critical Code:

Avoid complex flow constructs, such as goto and recursion.

All loops must have fixed bounds. This prevents runaway code.

Avoid heap memory allocation.

Restrict functions to a single printed page.

Use a minimum of two runtime assertions per function.

Restrict the scope of data to the smallest possible.

Check the return value of all non-void functions, or cast to void to indicate the return value is useless.

Use the preprocessor sparingly.

Limit pointer use to a single dereference, and do not use function pointers.

Compile with all possible warnings active; all warnings should then be addressed before release of the software.

https://en.m.wikipedia.org/wiki/The_Power_of_10:_Rules_for_Developing_Safety-Critical_Code

Prime Number on Python

We've done it using Delphi, how about Python? Easy, :)

for i in range (2,200):
    prime = True
    for j in range (2,i):
        if i%j==0: 
            prime=False
    if prime==True:
        print i

.

Prime Number on Delphi

Using Delphi to generate prime number? Okay, there's some code out there with

if (i mod 2 <>0) and (i mod 3 <>0) and (i mod 5 <>0) and (i mod 7 <>0) then i is prime.

Don't use that.

That's just for prime number below 100.

Use this instead.

var i,j:integer;
   prime:boolean;
begin
  for i:=2 to 200 do begin
    prime:=true;
    for j:=2 to i-1 do begin
      if i mod j=0 then prime:=false;
    end;
    if prime=true then memo1.Lines.Append(intToStr(i));
  end;
end;

.

Rutinitas Sore.

Buka pintu garasi. 

Disambut Alfa Beta.

Memasukkan si ducati sambil dengar mereka cerita tentang hari mereka.

Dikasih sandal sama Beta saat lepas sepatu, sambil dengar rentetan cerita Alfa tentang di sekolah dan di rumah Budhe yang diulang persis sama Beta.

Masuk rumah, mandi, makan sambi baca buku, cerita mereka belum habis.

Kruntelan serumah, diiringi Sophia, Mickey dkk, Kion, Bunga, Beasty, PJ Mask, Captain Jack, ...

Jam tujuh Alfa minta makan, didulang ayah. Beta minta susu dan iPad buat pengantar tidur.

Jam delapan Alfa migrasi dari depan tipi ke kamar, nonton tipi di kasur, semua lampu padam kecuali kamar Beta.

Dan tertidurlah Alfa.

Lampu kamar loteng nyala, sound-mixer nyala, dengan gitar/piano/bass. Main musik sampai ngantuk atau sampai jari bengkak.

Lanjut baca e-book sampai terbangun oleh alarm pagi, :D