几行代码生成漂亮图片，数学家就是牛！

  1 // NOTE: compile with g++ filename.cpp -std=c++11  
  2 #include <iostream>
  3 #include <cmath>
  4 #include <cstdlib> 
  5 #define DIM 1024 
  6 #define DM1 (DIM-1) 
  7 #define _sq(x) ((x)*(x)) // square 
  8 #define _cb(x) abs((x)*(x)*(x)) // absolute value of cube 
  9 #define _cr(x) (unsigned char)(pow ((x),1.0/3.0)) // cube root
 10 #define F
 11  
 12 unsigned char GR (int,int);
 13 unsigned char BL (int,int);
 14  
 15 unsigned char RD (int i,int j){
 16     #ifdef A
 17     return (char)(_sq(cos(atan2(j-512,i-512)/2))*255);
 18     #endif
 19 
 20     #ifdef B
 21     #define r(n) (rand ()%n) 
 22     static char c[1024][1024];
 23     return!c[i][j]?c[i][j]=!r(999)?r(256):RD ((i+r(2))%1024,(j+r(2))%1024):c[i][j];
 24     #endif
 25 
 26     #ifdef C
 27     float x=0,y=0;
 28     int k;
 29     for(k=0;k++<256;){
 30         float a=x*x-y*y+ (i-768.0)/512;
 31         y=2*x*y+ (j-512.0)/512;
 32         x=a;
 33         if(x*x+y*y>4)break;
 34     }
 35     return log (k)*47;
 36     #endif
 37 
 38     #ifdef D
 39     double a=0,b=0,c,d,n=0;
 40     while((c=a*a)+(d=b*b)<4&&n++<880){
 41         b=2*a*b+j*8e-9-.645411;
 42         a=c-d+i*8e-9+.356888;
 43     }
 44     return 255*pow ((n-80)/800,3.);
 45     #endif
 46 
 47     #ifdef E
 48     static double k;
 49     k+=rand ()/1./RAND_MAX;
 50     int l=k;
 51     l%=512;
 52     return l>255?511-l:l;
 53     #endif
 54 
 55     #ifdef F
 56     float s=3./(j+99);
 57     float y=(j+sin ((i*i+_sq (j-700)*5)/100./DIM)*35)*s;
 58     return (int((i+DIM)*s+y)%2+int((DIM*2-i)*s+y)%2)*127;
 59     #endif
 60 /*
 61     #ifdef G
 62     #define D DIM 
 63     #define M m[(x+D+ (d==0)-(d==2))%D][(y+D+ (d==1)-(d==3))%D] 
 64     #define R rand ()%D 
 65     #define B m[x][y] 
 66     return(i+j)?256-(BL (i,j))/2:0;
 67     #endif
 68 */
 69 /*
 70     #ifdef H
 71     #define A float a=0,b,k,r,x 
 72     #define B int e,o 
 73     #define C (x) x>255?255:x 
 74     #define R return #define D DIM 
 75     R BL (i,j)*(D-i)/D;
 76     #endif
 77 */
 78     return 0;
 79 }
 80 unsigned char GR (int i,int j){
 81     #ifdef A
 82     return (char)(_sq (cos (atan2(j-512,i-512)/2-2*acos (-1)/3))*255);
 83     #endif
 84 
 85     #ifdef B
 86     static char c[1024][1024];
 87     return!c[i][j]?c[i][j]=!r(999)?r(256):GR ((i+r(2))%1024,(j+r(2))%1024):c[i][j];
 88     #endif
 89 
 90     #ifdef C
 91     float x=0,y=0;
 92     int k;
 93     for(k=0;k++<256;){
 94         float a=x*x-y*y+ (i-768.0)/512;
 95         y=2*x*y+ (j-512.0)/512;
 96         x=a;
 97         if(x*x+y*y>4)break;
 98     }
 99     return log (k)*47;
100     #endif
101 
102     #ifdef D
103     double a=0,b=0,c,d,n=0;
104     while((c=a*a)+(d=b*b)<4&&n++<880){
105         b=2*a*b+j*8e-9-.645411;
106         a=c-d+i*8e-9+.356888;
107     }
108     return 255*pow ((n-80)/800,.7);
109     #endif
110 
111     #ifdef E
112     static double k;
113     k+=rand ()/1./RAND_MAX;
114     int l=k;
115     l%=512;
116     return l>255?511-l:l;
117     #endif
118 
119     #ifdef F
120     float s=3./(j+99);
121     float y=(j+sin ((i*i+_sq (j-700)*5)/100./DIM)*35)*s;
122     return (int(5*((i+DIM)*s+y))%2+int(5*((DIM*2-i)*s+y))%2)*127;
123     #endif
124 /*
125     #ifdef G
126     #define A 
127     static int m[D][D],e,x,y,d,c[4],f,n;
128     if (i+j<1){
129         for (d=D*D;d;d--){
130             m[d%D][d/D]=d%6?0:rand ()%2000?1:255;
131         }
132         for (n=1 return RD (i,j);
133     #endif
134 */
135 /*
136     #ifdef H
137     #define E DM1 
138     #define F static float 
139     #define G for ( 
140     #define H r=a*1.6/D+2.4;x=1.0001*b/D
141     R BL (i,j)*(D-j/2)/D;
142     #endif
143 */
144     return 0;
145 }
146 unsigned char BL (int i,int j){
147     #ifdef A
148     return (char)(_sq (cos (atan2(j-512,i-512)/2+2*acos (-1)/3))*255);
149     #endif
150 
151     #ifdef B
152     static char c[1024][1024];
153     return!c[i][j]?c[i][j]=!r(999)?r(256):BL((i+r(2))%1024,(j+r(2))%1024):c[i][j];
154     #endif
155 
156     #ifdef C
157     float x=0,y=0;
158     int k;
159     for(k=0;k++<256;){
160         float a=x*x-y*y+ (i-768.0)/512;
161         y=2*x*y+ (j-512.0)/512;
162         x=a;
163         if(x*x+y*y>4)break;
164     }
165     return 128-log (k)*23;
166     #endif
167 
168     #ifdef D
169     double a=0,b=0,c,d,n=0;
170     while((c=a*a)+(d=b*b)<4&&n++<880){
171         b=2*a*b+j*8e-9-.645411;
172         a=c-d+i*8e-9+.356888;
173     }
174     return 255*pow ((n-80)/800,.5);
175     #endif
176 
177     #ifdef E
178         static double k;
179         k+=rand ()/1./RAND_MAX;
180         int l=k;
181         l%=512;
182         return l>255?511-l:l;
183     #endif    
184 
185     #ifdef F
186     float s=3./(j+99);
187     float y=(j+sin ((i*i+_sq (j-700)*5)/100./DIM)*35)*s;
188     return (int(29*((i+DIM)*s+y))%2+int(29*((DIM*2-i)*s+y))%2)*127;
189     #endif
190 /*
191     #ifdef G
192     A;n;n++){
193         x=R;y=R;
194         if(B==1){
195             f=1;
196             for(d=0;d<4;d++){
197                 c[d]=M;
198                 f=f<c[d]?c[d]:f;
199             }
200             if(f>2){B=f-1;}
201             else{
202                 ++e%=4;
203                 d=e;
204                 if(!c[e]){
205                     B=0;M=1;
206                 }}}}}
207     return m[i][j];
208     #endif
209 */
210 /*
211     #ifdef H
212     F c[D][D];
213     if(i+j<1){A;B;G;a<D;a+=0.1){G b=0;b<D;b++){H;G k=0;k<D;k++){x=r*x*(1-x);
214     if(k>D/2){e=a;o=(E*x);c[e][o]+=0.01;}}}}}
215     R C (c[j][i])*i/D;
216     #endif
217 */
218 
219     return 0;
220 }
221  
222 void pixel_write (int,int);
223 FILE *fp;
224 int main (){
225     fp = fopen ("MathPic.ppm","wb");
226     fprintf (fp, "P6\n%d %d\n255\n", DIM, DIM);
227     for(int j=0;j<DIM;j++)
228         for(int i=0;i<DIM;i++)
229             pixel_write (i,j);
230     fclose (fp);
231     return 0;
232 }
233 void pixel_write (int i, int j){
234     static unsigned char color[3];
235     color[0] = RD (i,j)&255;
236     color[1] = GR (i,j)&255;
237     color[2] = BL (i,j)&255;
238     fwrite (color, 1, 3, fp);
239 }