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1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <math.h>
4
5 #define X 2560 //尽量为8的倍数，若不是X/8需向上取整
6 #define Y 1600 //推荐X、Y比例为(4.0-2.4):1，这样网格为正方形
7
8
9 #define b_start 2.4
10 #define b_end 4.0
11 #define b_len (b_end-b_start)
12
13 #define PI 3.14159265358979323846
14 #define function(_b, _x) (_b*sin(_x*PI)/4)
15 //迭代方程
16 //x = b*x*(1-x) (_b*_x*(1-_x))
17 //x = b/4*sin(x/pi) (_b*sin(_x*PI)/4)
18 int main(int argc, char **argv)
19 {
20 double x;
21 if(argc==2)
22 x = atof(argv[1]);
23 else
24 x = 0.6;
25
26 unsigned char * data = (unsigned char *)calloc(X*Y/8, 1);
27
28 double b = b_start;
29 for(int i=0;i<X;i++){ //保证x轴取点密度
30 double temp = x;
31 for(int k=0;k<4000;k++){ //先迭代至基本稳定
32 temp = function(b, temp);
33 }
34 for(int k=0;k<1000;k++){ //真正画的部分
35 temp = function(b, temp);
36 int vx = (b-b_start)/b_len*X; //visual(virtual) x
37 int vy = temp*Y; //visual(virtual) y
38 data[(Y-1-vy)*(X/8)+vx/8] |= 1<<(7-vx%8);
39 }
40 b += b_len/X;
41 }
42 //画竖线
43 for(double i=b_start;i<b_end;i+=0.1){
44 int vx = (i-b_start)/b_len*X; //visual(virtual) x
45 for(int vy=0;vy<Y;vy++){
46 data[(Y-1-vy)*(X/8)+vx/8] |= 1<<(7-vx%8);
47 }
48 }
49 //画横线
50 for(double i=0;i<1;i+=0.1){
51 int vy = i*Y; //virsual(virtual) y
52 for(int vx=0;vx<X;vx++){
53 data[(Y-1-vy)*(X/8)+vx/8] |= 1<<(7-vx%8);
54 }
55 }
56 //图片输出
57 FILE *fp;
58 fp = fopen("0.25 sin(PI x).pbm","wb");
59 fprintf(fp, "P4 %d %d\n", X, Y);
60 for(int i=0; i<X*Y/8; i++)
61 fputc(data[i], fp);
62 fclose(fp);
63
64 free(data);
65 return 0;
66 }
Demo
x = b * x * (1 - x)
x = b / 4 * sin(PI * x)
标签：Map,int,char,start,Logistic,PI,sin,define From： https://www.cnblogs.com/YHFBlogs/p/16609824.html