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exercise4.c
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exercise4.c
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/* =================================================================
mandelbrot-serial.c
Written by Frederick Fung for NCI OpenMP Workshop March 2022
This program computes Mandelbrot set within a pre-defined region.
For plotting, the output is filled as the iteration goes.
Output: an 2D array. Each element corresponds to a pixel to be drawn.
Compile: gcc -g -Wall -O3 -o mandelbrot-serial mandelbrot-serial.c
Usage: ./mandelbrot-serial
.....................................................................
Produced for NCI Training.
Frederick Fung 2022
4527FD1D
====================================================================*/
#include<stdio.h>
#include<stdlib.h>
#include <time.h>
#include<omp.h>
//#include "gnuplot-iostream.h"
#define MAXITER 100
//#define OPENMP_TIMER
/* struct for complex number */
struct complex{
double real;
double img;
};
struct complex c_num;
int convergence_check(struct complex c_num){
struct complex z_num;
z_num.real =0;
z_num.img =0;
double temp;
for (int i =0; i< MAXITER; i++){
double fx;
temp = z_num.real * z_num.real - z_num.img * z_num.img + c_num.real;
z_num.img = 2 * z_num.real * z_num.img + c_num.img;
z_num.real = temp;
fx = z_num.real * z_num.real + z_num.img * z_num.img;
/* if escapes, records the iter */
if (fx > 4.0f ) return i;
}
// failed to escape
return 0;
}
void gen_mandelbrot(const int *points){
char path[100];
sprintf(path, "mandelbrot_set_%d.csv", *points);
FILE *fp;
fp = fopen(path, "w+");
int i, j;
int NPOINTS = *points;
/* steps between points */
double step_i = (double) (2.0+0.47) / NPOINTS;
double step_j = (double) (1.12+1.12) / NPOINTS;
for (i = 0; i< NPOINTS; i++){
for (j = 0; j< NPOINTS; j++){
int iter;
c_num.real = -2.0 + i* step_i;
c_num.img = -1.12 + j* step_j;
iter = convergence_check(c_num);
fprintf(fp, "%d,", iter);
}
fprintf(fp, "\n");
}
}
int main(){
int npoints_array[]= {100,1000,10000};
for (int i=0; i< sizeof(npoints_array) / sizeof(npoints_array[0]); i++){
int point = npoints_array[i];
printf("Resolution #%d, Points %d by %d \n", i, point, point);
gen_mandelbrot(&point);
}
}