+ /* Provide for the four cases in which there's a glitch */
+ /* it's a hack, but probably not worth */
+ /* the effort of finding a nicer solution. dl. */
+ if (c0==2 && a>0 && p==3)
+ p -= 7;
+ if (c0==-3 && a>0 && p==-1)
+ p += 7;
+ if (c0==-4 && a<0 && p==-1)
+ p += 7;
+ if (c0==-2 && a<0 && p==-3)
+ p += 7;
+
+ return p + c0;