private static bool test01()
//****************************************************************************80
//
// Purpose:
//
// TEST01 tests PPMA_EXAMPLE and PPMA_WRITE.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 27 May 2011
//
// Author:
//
// John Burkardt
//
{
const string file_out_name = "test01.ascii.ppm";
const int xsize = 300;
const int ysize = 300;
Console.WriteLine("");
Console.WriteLine("TEST01:");
Console.WriteLine(" PPMA_EXAMPLE sets up PPM data.");
Console.WriteLine(" PPMA_WRITE writes an ASCII PPM file.");
Console.WriteLine("");
Console.WriteLine(" Writing the file \"" + file_out_name + "\".");
int[] r = new int[xsize * ysize];
int[] g = new int[xsize * ysize];
int[] b = new int[xsize * ysize];
bool error = PPM_ASCII.ppma_example(xsize, ysize, ref r, ref g, ref b);
switch (error)
{
case true:
Console.WriteLine("");
Console.WriteLine("TEST01 - Fatal error!");
Console.WriteLine(" PPMA_EXAMPLE failed!");
return(true);
}
Console.WriteLine("");
Console.WriteLine(" PPMA_EXAMPLE has set up the data.");
error = PPM_ASCII.ppma_write(file_out_name, xsize, ysize, r, g, b);
switch (error)
{
case true:
Console.WriteLine("");
Console.WriteLine("TEST01 - Fatal error!");
Console.WriteLine(" PPMA_WRITE failed!");
return(true);
}
Console.WriteLine("");
Console.WriteLine(" PPMA_WRITE was successful.");
//
// Now have PPMA_READ_TEST look at the file we think we created.
//
error = PPM_ASCII.ppma_read_test(file_out_name);
switch (error)
{
case true:
Console.WriteLine("");
Console.WriteLine("TEST01 - Fatal error!");
Console.WriteLine(" PPMA_READ_TEST failed to read the file we wrote!");
return(true);
}
Console.WriteLine("");
Console.WriteLine(" PPMA_READ_TEST was able to read the file we wrote.");
return(false);
}
private static void Main()
//****************************************************************************80
//
// Purpose:
//
// MAIN is the main program for MANDELBROT.
//
// Discussion:
//
// MANDELBROT computes an image of the Mandelbrot set.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 22 July 2010
//
// Author:
//
// John Burkardt
//
// Local Parameters:
//
// Local, integer COUNT_MAX, the maximum number of iterations taken
// for a particular pixel.
//
{
const int count_max = 400;
const string filename = "mandelbrot.ppm";
int i;
int j;
const int n = 501;
const double x_max = 1.25;
const double x_min = -2.25;
const double y_max = 1.75;
const double y_min = -1.75;
Console.WriteLine("");
Console.WriteLine("MANDELBROT");
Console.WriteLine("");
Console.WriteLine(" Create an ASCII PPM image of the Mandelbrot set.");
Console.WriteLine("");
Console.WriteLine(" For each point C = X + i*Y");
Console.WriteLine(" with X range [" + x_min + "," + x_max + "]");
Console.WriteLine(" and Y range [" + y_min + "," + y_max + "]");
Console.WriteLine(" carry out " + count_max + " iterations of the map");
Console.WriteLine(" Z(n+1) = Z(n)^2 + C.");
Console.WriteLine(" If the iterates stay bounded (norm less than 2)");
Console.WriteLine(" then C is taken to be a member of the set.");
Console.WriteLine("");
Console.WriteLine(" An ASCII PPM image of the set is created using");
Console.WriteLine(" N = " + n + " pixels in the X direction and");
Console.WriteLine(" N = " + n + " pixels in the Y direction.");
//
// Carry out the iteration for each pixel, determining COUNT.
//
int[] count = new int[n * n];
for (i = 0; i < n; i++)
{
for (j = 0; j < n; j++)
{
double x = (j * x_max
+ (n - j - 1) * x_min)
/ (n - 1);
double y = (i * y_max
+ (n - i - 1) * y_min)
/ (n - 1);
count[i + j * n] = 0;
double x1 = x;
double y1 = y;
int k;
for (k = 1; k <= count_max; k++)
{
double x2 = x1 * x1 - y1 * y1 + x;
double y2 = 2 * x1 * y1 + y;
if (x2 is < -2.0 or > 2.0 || y2 is < -2.0 or > 2.0)
{
count[i + j * n] = k;
break;
}
x1 = x2;
y1 = y2;
}
}
}
//
// Determine the coloring of each pixel.
//
int c_max = 0;
for (j = 0; j < n; j++)
{
for (i = 0; i < n; i++)
{
if (c_max < count[i + j * n])
{
c_max = count[i + j * n];
}
}
}
//
// Set the image data.
//
int[] r = new int[n * n];
int[] g = new int[n * n];
int[] b = new int[n * n];
for (i = 0; i < n; i++)
{
for (j = 0; j < n; j++)
{
int index = i + j * n;
switch (count[i + j * n] % 2)
{
case 1:
r[index] = 255;
g[index] = 255;
b[index] = 255;
break;
default:
{
int c = (int)(255.0 * Math.Sqrt(Math.Sqrt(Math.Sqrt(
count[i + j * n] / (double)c_max))));
int v = 3 * c / 5;
r[index] = v;
g[index] = v;
b[index] = c;
break;
}
}
}
}
//
// Write an image file.
//
PPM_ASCII.ppma_write(filename, n, n, r, g, b);
Console.WriteLine("");
Console.WriteLine(" ASCII PPM image data stored in \"" + filename + "\".");
Console.WriteLine("");
Console.WriteLine("MANDELBROT");
Console.WriteLine(" Normal end of execution.");
Console.WriteLine("");
}