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From: jeroenk@cnps.PHILIPS.nl (Jeroen Kessels)
Newsgroups: comp.lang.pascal
Subject: Re: TP: Exponentiation?
Message-ID: <1256@cnps.PHILIPS.nl>
Date: 25 Jul 90 11:35:09 GMT
References: <950036@hpclapd.HP.COM>
Organization: Philips C&P-LSS
Lines: 38

defaria@hpclapd.HP.COM (Andy DeFaria) writes:

> how to you do exponentiation in TP 4.0  (or 5.0 or 5.5).
> ...
> the usually "**" operator only produced a compile error.  What gives?

If you mean 'exponential' (e raised to the x'th power) then try the
'exp()' function. If you mean 'exponentiate' (x raised to the y'th
power) then you could use the following function of mine, there is no
ready-made function.


{$N+}

function Power(x, y : extended) : extended;
{ Return x to the power of y. Note: a non-integer power of a negative
  number is not defined in mathematics. This routine will therefore
  round y to an integer if x is negative. }
var
  i : longint;
begin
if x > 0
  then Power := exp(y*ln(x))
  else if x = 0.0
    then Power := 0.0
    else
      begin
      i := round(int(y));
      if odd(i)
        then Power := -exp(ln(abs(x)) * i)
        else Power := exp(ln(abs(x)) * i);
      end;
end;
-- 
Jeroen C. Kessels
Software Engineer, Philips C&P-LSS
VA-25, P.O. Box 218, 5600 MD Eindhoven, The Netherlands
Uucp = jeroenk@cnps.philips.nl