To all Question:When is a bug not a bug: Answer: When it is a feature. Example: Fractints integer artifacts. I had a computer with one of the defective Pentiums and in years of calculating I never saw any problem due to it. I ran into something when I wrote my first Mandelbrot formula. I ended up with a central high count feature that looked like a three blade airplane propeller. The formula is in the Orgform collection under the name Prop, along with several variants. I always blamed it on a defect in the double precision ROM routines in the TRS80. The actual problem was that the imaginary component got it's sign reversed at every iteration. I really can't say whether the real problem was me, the ROM, or the documentation I had. Since then I have seen the same figure in two other Fractint formulas. I have lost one of them but the other, a totally different formula, produces precisely the same result. This looks strange to me. My conclusion? When you are dealing with endless repetitions on infinitesimal quantities anything can and does happen. Who can say what is right and what is wrong? Charles