/**************************************************************************
* FRACTALS: SET OF MANDELBROT *
* ----------------------------------------------------------------------- *
* TUTORIAL: *
* *
* The set of Mandelbrot is a figure in the complex plane, that is (for no *
* mathematicians) the plane allowing to represent complex numbers having *
* the form a + i b, a is the real part (ox componant) and b is the *
* imaginary part (oy componant). The imaginary number i is the unity of *
* axis oy, defined as i x i = -1. In the following, we will use the *
* multiplication of two complex numbers and the module value of a complex *
* number before defining the set of Mandelbrot itself. *
* *
* Multiply z1 by z2 *
* *
* Let be z1 = a1 + i b1 and z2 = a2 + i b2, two complex numbers. To cal- *
* culate Z = z1 x z2, one just has to algebraically develop the expression*
* (a1 + i b1)*(a2 + i b2), replacing i² by -1 and separating constant *
* terms from i terms. One easily obtains: *
* *
* Z = (a² - b²) + i (2ab) *
* *
* Module of a complex number *
* *
* Every complex number a + i b can be represented as the point of coordi- *
* nates (a, b) in the complex plane. Its module is nothing other than the *
* distance of this point from origin (0,0), that is to say: *
* *
* | Z | = square root of (a² + b²) *
* *
* We can now define the iterative process that will lead us to the magni- *
* ficent "Set of Mandelbrot": *
* *
* We take, as a starting point, a fixed complex number c, and we calculate*
* the complex expression z² + c, z being a variable complex number. *
* Let us take z = 0, then z² + c equals c. Let us replace z by c in the *
* formula z² + c, then we obtain c² + c. Let us again remplace z by this *
* new value, then we obtain (c²+c)² + c. Such a process is indefinitly *
* resumed, each new value z² + c is taken as new value z. This provides *
* an unlimited series of z numbers. *
* *
* The mathematician Mandelbrot was the first to notice that, according to *
* the chosen value c, the series of complex numbers z so obtained could *
* have a module, either rapidly tending towards infinity, or tending *
* towards a finite value, whatever the number of iterations may be. *
* *
* Two examples: *
* *
* 1) c = 1 + i *
* *
* iteration new z module of z *
* ____________________________________________ *
* 1 1 + 3i 3,16227... *
* 2 -7 + 7i 9,89949... *
* 3 1-97i 97,00515... *
* 4 -9407-193i 9408,97965 *
* *
* The module of z increases very rapidly. *
* *
* 2) c = -1 + 0,25 i *
* *
* iteration new z module de z *
* ____________________________________________ *
* 1 -0,5 - 0i 0,5 *
* 2 -0,25 + 0,5i 0,55902... *
* 3 -0,687 + 0,25i 0,73154... *
* *
* At 80th iteration, z = 0.40868 + 0,27513 i, the module equals 0,49266...*
* The module remains with a finite value, whatever the number of itera- *
* tions may be. Practically, we will consider that the limit is obtained *
* after 100 iterations, if the module of z is < 4. The set of Mandelbrot, *
* still called the Mandelbrot man, because of its shape, is constituted *
* by all the points for which the expression z² + c has a finite value *
* whatever the number of iterations may be. *
* *
* See also programs mandbrot.pas and julia.pas. *
* *
* ----------------------------------------------------------------------- *
* REFERENCE: *
* "Graphisme dans le plan et dans l'espace avec Turbo Pascal 4.0 *
* By R. Dony - MASSON, Paris 1990" [BIBLI 12]. *
* *
* Visual C++ version by J-P Moreau *
* (to be used with mandel.mak and Gr2d.cpp) *
* (www.jpmoreau.fr) *
**************************************************************************/
#include
#include
#include
#include
HDC hdc;
RECT rect;
//"home made" graphic commands for hdc environment used by above functions
void DrawPixel(int ix,int iy) {
//sorry, no other available command found
Rectangle(hdc,rect.left+ix,rect.top+iy,
rect.left+ix+2,rect.top+iy+1);
}
void Swap(int *i1,int *i2) {
int it;
it=*i1; *i1=*i2; *i2=it;
}
void DrawLine(int ix1,int iy1,int ix2,int iy2) {
int i,il,ix,iy;
float dx,dy;
if (ix2