fix small bug in mandel.c

2torus · 2torus · commit caca1dc5caeb · 2019-06-05T23:36:53.000+03:00
diff --git a/mandel.c b/mandel.c
@@ -9,8 +9,9 @@ int mandel(float x, float y, int max_iters, unsigned char * val)
     for (i = 0; i < max_iters; i++)
     {
         /* in complex notation, z * z + c */
+	float prev_zR = zR;
         zR = zR * zR - zI * zI + cR;
-        zI = 2 * zR * zI + cI;
+        zI = 2 * prev_zR * zI + cI;
         if ((zR * zR + zI * zI) >= 4)
         {
             *val = i;

Original file line number	Diff line number	Diff line change
`@@ -9,8 +9,9 @@ int mandel(float x, float y, int max_iters, unsigned char * val)`
`9`	`9`	`for (i = 0; i < max_iters; i++)`
`10`	`10`	`{`
`11`	`11`	`/* in complex notation, z * z + c */`
	`12`	`+ float prev_zR = zR;`
`12`	`13`	`zR = zR * zR - zI * zI + cR;`
`13`		`- zI = 2 * zR * zI + cI;`
	`14`	`+ zI = 2 * prev_zR * zI + cI;`
`14`	`15`	`if ((zR * zR + zI * zI) >= 4)`
`15`	`16`	`{`
`16`	`17`	`*val = i;`