mandelbrot: make mincol description and code match.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/vsrc_mandelbrot.c

@@ -98,7 +98,7 @@ static const AVOption mandelbrot_options[] = {
     {"black",       "set black mode",                0, AV_OPT_TYPE_CONST, {.dbl=BLACK}, INT_MIN, INT_MAX, 0, "inner" },
     {"period",      "set period mode",               0, AV_OPT_TYPE_CONST, {.dbl=PERIOD}, INT_MIN, INT_MAX, 0, "inner" },
     {"convergence", "show time until convergence",   0, AV_OPT_TYPE_CONST, {.dbl=CONVTIME}, INT_MIN, INT_MAX, 0, "inner" },
-    {"mincol",      "color based on point closest to the origin of the cycle",   0, AV_OPT_TYPE_CONST, {.dbl=MINCOL}, INT_MIN, INT_MAX, 0, "inner" },
+    {"mincol",      "color based on point closest to the origin of the iterations",   0, AV_OPT_TYPE_CONST, {.dbl=MINCOL}, INT_MIN, INT_MAX, 0, "inner" },
 
     {NULL},
 };
@@ -275,7 +275,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
                     int j;
                     double closest=9999;
                     int closest_index=0;
-                    for(j=i-1; j; j--)
+                    for(j=i-1; j>=0; j--)
                         if(SQR(mb->zyklus[j][0]) + SQR(mb->zyklus[j][1]) < closest){
                             closest= SQR(mb->zyklus[j][0]) + SQR(mb->zyklus[j][1]);
                             closest_index= j;