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From: Florian Weimer <fw@cygnus.stuttgart.netsurf.de>
Subject: Re: Ada95 speed
Date: 1999/05/18
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"Clifford J. Nelson" <cnelson9@gte.net> writes:

> Ten years ago a Mandelbrot set computation and display on a 1200x700
> screen with eight bit color took six seconds in C on a MacIIfx.

You obviously used a different algorithm.

>           exit when (abs( Z)) > 2.0;

This statement is executed approximately 6 million times.  Calculating
the absolute value of a complex number involves taking a square root.
This is a very expensive operation and dominates the running time by far.

I'd suggest to square both sides of the inequation and use:

          exit when (Z.Re * Z.Re + Z.Im * Z.Im) > 4.0;

I suppose your C code does exactly that because C hasn't got built-in
complex types, so this optimization is more obvious.