{─ Fido Pascal Conference ────────────────────────────────────────────── PASCAL ─
Msg  : 430 of 473
From : Erik Johnson                        1:104/28.0           13 Apr 93  19:52
To   : David Jirku
Subj : FAST MATH
────────────────────────────────────────────────────────────────────────────────
>        I was just wondering how to speed up some math-intensive
>        routines I've got here. For example, I've got a function
>        that returns the distance between two objects:
>
>        Function Dist(X1,Y1,X2,Y2 : Integer) : Real;
>
>        BEGIN
>          Dist := Round(Sqrt(Sqr(X1-X2)+Sqr(Y1-Y2)));
>        END;
>
>        This is way to slow. I know assembly can speed it up, but
>        I know nothing about asm. so theres the problem. Please
>        help me out, any and all source/suggestions welcome!

X1, Y1, X2, Y2 are all integers.  Integer math is faster than Real (just
about anything is).  Sqr and Sqrt are not Integer functions.  Try for
fun...     }

Function Dist( X1, Y1, X2, Y2 : Integer ) : Real;
VAR XTemp, YTemp : INTEGER; {the allocation of these takes time.  If you
                             don't want that time taken, make them
                             global with care}
BEGIN
  XTemp := X1 - X2;
  YTemp := Y1 - Y2;
  Dist := Round( Sqrt( XTemp*XTemp + YTemp*YTemp ));
END;

If you have a math coprocessor or a 486dx, try using DOUBLE instead of
REAL, and make sure your compiler is set to compile for 287 (or 387).