Jonathan and Tim, I think I've stumbled upon the reason why "julibrot" subtypes "quat" and "hypercomplex" don't render correctly - it seems to be a simple case of wrong initialization in zlinefp() in file jb.c. However, my knowledge of Fractint's source is minimal at best, so its possible the fix is not complete (although all works nicely with the executable produced by *cough* old Borland C/C++ 3.1). Since the diff is small it's directly pasted below this text (hope this is ok). Regards, Gerald ------------------------ jb.c.diff --------------------------- *** jb.c Sun Jan 18 07:19:34 2004 --- ..\jb.c Fri Feb 13 06:27:48 2004 *************** *** 308,319 **** for (zpixel = 0; zpixel < zdots; zpixel++) { ! old.x = jxfp; ! old.y = jyfp; ! jbcfp.x = mxfp; ! jbcfp.y = myfp; ! qc = param[0]; ! qci = param[1]; ! qcj = param[2]; ! qck = param[3]; #ifdef XFRACT if (keychk++ > 500) --- 308,334 ---- for (zpixel = 0; zpixel < zdots; zpixel++) { ! /* Special initialization for Mandelbrot types */ ! if (neworbittype == QUATFP || neworbittype == HYPERCMPLXFP) ! { ! old.x = 0.0; ! old.y = 0.0; ! jbcfp.x = 0.0; ! jbcfp.y = 0.0; ! qc = jxfp; ! qci = jyfp; ! qcj = mxfp; ! qck = myfp; ! } ! else ! { ! old.x = jxfp; ! old.y = jyfp; ! jbcfp.x = mxfp; ! jbcfp.y = myfp; ! qc = param[0]; ! qci = param[1]; ! qcj = param[2]; ! qck = param[3]; ! } #ifdef XFRACT if (keychk++ > 500) --------------------- end of jb.c.dif ------------------------