From

http://smalltalk.gnu.org/blog/bonzinip/all-you-should-really-know-about-autoconf-and-automake

A very good description of a simple use of autoconf and automake:

The problem with autotools is that it is used for complicated things, and people cut-and-paste complicated things even when they ought to be simple. 99% of people just need a way to access .pc files and generate juicy Makefiles, the portability part is taken care by glib, sdl and so on.

The most basic autotools setup is 9 lines.

configure.ac:

AC_INIT([package], [version])
AM_INIT_AUTOMAKE([foreign subdir-objects])
AC_CONFIG_SRCDIR([configure.ac])
AC_CONFIG_HEADERS([config.h])     # not really needed
AC_PROG_CC                        # or AC_PROG_CXX
AC_CONFIG_FILES([Makefile])
AC_OUTPUT

Makefile.am:

bin_PROGRAMS = hello
hello_SOURCES = hello.c

And you’re ready for:

$ autoreconf -fvi
$ ./configure
$ make

On top of this, for each package you need, you add:

PKG_CHECK_MODULES([cairo], [cairo])
PKG_CHECK_MODULES([fontconfig], [fontconfig])

AM_CFLAGS = $(cairo_CFLAGS) $(fontconfig_CFLAGS)
LIBS += $(cairo_LIBS) $(fontconfig_LIBS)

respectively in configure.ac (after AC_PROG_CC) and Makefile.am. Is that complicated?

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I recently had a disk go bad in my iMac. The disk would often boot if the computer was cold but then would start having errors as it warmed up and … corrupting files.

I have never had to test any of my Time Machine backups for a real purpose. I was concerned that I would find that not all the files I needed would be restored or I would find I only really had partial backups. I have had many bad experiences over the years with untested backups, including backups done by sys admins. So I doubted that Apple’s magic backup would be complete.

So I stuck a blank hard disk in the machine and booted the 10.5 install CD. At this point you have two options, install a fresh copy of Mac OS X and restore your files and settings, or just restore everything from Time Machine. I chose to restore everything from Time Machine, started it and went to bed.

I was pleasantly surprised to find a complete restore. I had to resync my dot mac data and a couple little things. The worst one was the ~/Library/Caches directory was not created with permissions for me to write to it. But overall, I was very happy.

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Here is a site that provides an easy way to generate equation bitmaps online.

http://www.codecogs.com/components/equationeditor/equationeditor.php

In HTML and actually many environments there is no good way to write complex mathematical equations. Many people fall back to latex to generate bitmaps. This site lets you interactively click on the parts of the equation and generates both the latex and corresponding bitmaps.

So for example, I was trying to save some of my Kalman filter notes. I click edited the Predictor equation and it generated this bitmap:

And it generated this latex:

X^{*}_{n+1,n} = \phi X^{*}_{n,n}

Pretty nice.

Here is a simple example of code to use an OpenGL Texture.

// Apple gcc program0.c -framework opengl -framework glut
// A simple OpenGL and glut program
#include  /* Header File For The GLut Library*/
#include 

//
// You need to generate the texture data that you are going to
// use. GIMP will convert a bitmap, jpg, etc. to a "C" structure
// that you can use almost directly.
//

// GIMP RGBA C-Source image dump (f35_schem_02_edit_4.c) 

static const struct {
  uint32_t     width;
  uint32_t     height;
  uint32_t     bytes_per_pixel; /* 3:RGB, 4:RGBA */
  uint8_t      pixel_data[128 * 128 * 4 + 1];
} planform = {
  128, 128, 4,
  "\377\377\377\377\377\377\377"
  "\377\377\377\377\377\377\377"
  "\377\377\377\377\377\377\377"
  "\377\377\377\377\377\377\377\377"
  // ... much of the texture deleted
  "\377\377\377\377\377\377\377"
  "\377\377\377\377\377\377",
};

// The routine to draw the screen
void display() {
    // A value to hold our texture handle
    static uint32_t texture = 0;
    static int32_t  firstTimeDone = 0;

    // Clear the display
    glClear(GL_COLOR_BUFFER_BIT);
    // Set the color to white
    glColor3f(1.0, 1.0, 1.0);
    // Setup the coordinates to what I am used to
    glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0); 

    // Get a texture number if we dont have one
    if (!firstTimeDone)
    {
        // Get a texture number
        glGenTextures(1, &texture);

        // Tell OpenGL that we want to use that texture
        glBindTexture(GL_TEXTURE_2D, texture);

        // You have to tell OpenGL how to take the raw bitmap data
        // in the structure above to put it into a texture. We
        // do this with a glTexImage2D() call. We will describe the
        // structure above and how we want it stored internally in
        // OpenGl.
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, planform.width, planform.height,
            0, GL_RGBA, GL_UNSIGNED_BYTE, planform.pixel_data);

        // OpenGl lets you describe how you want to scale the
        // texture data when the destination is bigger or smaller
        // than the original texture data. In this case, we want
        // simple linear scaling.
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

        // First Time is done
        firstTimeDone = 1;
    }
    else
    {
        // Tell OpenGL that we want to use that texture
        glBindTexture(GL_TEXTURE_2D, texture);
    }

    // We are going to put the texture on a 2D surface, much
    // like we would apply a decal.
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

    // Normally you leave GL_TEXTURE_2D turned off unless
    // you are applying a decal to a surface. Since we are
    // doing that, we turn it on here.
    glEnable(GL_TEXTURE_2D);

    // Draw the square
    glBegin(GL_POLYGON);

    // Here we want to associate a point in the texture with the
    // vertex we are drawing on the screen. So these are paired up.
    glTexCoord2f(0.0f, 1.0f); glVertex2f(-0.5, -0.5);
    glTexCoord2f(0.0f, 0.0f); glVertex2f(-0.5, 0.5);
    glTexCoord2f(1.0f, 0.0f); glVertex2f(0.5, 0.5);
    glTexCoord2f(1.0f, 1.0f); glVertex2f(0.5, -0.5);

    // End of the list of verticies
    glEnd();
    // Turn texture drawing back off, normally we leave if off.
    glDisable(GL_TEXTURE_2D);

    // Flush the data. In many drivers, this causes the
    // actual draw to the Frame Buffer.
    glFlush();
} 

int main(int argc, char **argv) {
    // A minimal GLUT setup to get GLUT up and going.
    // If you use EGL or some other windowing system
    // other than GLUT, you need to replace this.
    glutInit(&argc, argv);
    glutInitWindowSize(512,512);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutCreateWindow("The glut hello world program");
    glutDisplayFunc(display);
    glClearColor(0.0, 0.0, 0.0, 1.0);
    glutMainLoop(); // Infinite event loop
    return 0;
} 

This is an example of how to parse a binary file in perl. This reads an mpeg-2 file and chops the first 8 Mbyte chunk out of the file, closing at the next clean sequence header boundary.

#! perl

use Getopt::Std;

use strict;

sub chopMpegFile
{
    my ($fileName) = @_;

    open FILE, "$fileName" or die "Could not open file: $!\n";
    open OUT,  ">out.mpg"   or die "Could not open file: $!\n";

    binmode(FILE);
    binmode(OUT);

    my $buffer = '';
    my $count  = 0;
    my $done   = 0;

    while ((! $done) && ( sysread(FILE, $buffer, 4) ))
    {
        my $value = unpack 'N', $buffer;
        if (($count++ > 2 * 1024 * 1024) && ($value == 0x000001b3))
        {
            print "Closing file.\n";
            $done = 1;
        }
        else
        {
            syswrite(OUT, $buffer, 4);
        }
        if (($count % (1024*100)) == 0)
        {
            print "Count $count\n";
        }
    }
    close(FILE);
    close(OUT);
}

my @args = splice(@ARGV, 0);
foreach my $arg (@args)
{
    print "$arg\n";
    &chopMpegFile($arg);
}