From: "A.Appleyard" <A DOT APPLEYARD AT fs2 DOT mt DOT umist DOT ac DOT uk>
To: DJGPP AT SUN DOT SOE DOT CLARKSON DOT EDU
Date: Thu, 11 May 1995 16:30:35 BST
Subject: pow()

#include<math.h>
main(){int i,j; double x,y;
pow(i,j);
pow(x,i);
pow(x,y);}

  This program compiled OK. I recompiled it with -E, to get the preprocessed
form (i.e. after obeying the #directives), and I found that of gcc's various
pow(,) functions, the #included matter only had pow(double,double). That means
that all pow(,), even pow(int,int) is called as exp(exponent*log(mantissa)).
This is very time-wasting for a small integer exponent obeyed many times.
  If I instead #include <builtin.h>, the #included matter also has pow(long
int,long int) and pow(double,long int), so that supposedly pow(,) with integer
exponent is obeyed by a quick method. But what actually happens is:-

C:\WORK>c:\djgpp\bin\gcc t$1.cc
t$1.cc: In function `int main()':
t$1.cc:3: call of overloaded `pow' is ambiguous
c:/djgpp/cplusinc/builtin.h:47: candidates are: pow(long int, long int)
c:/djgpp/cplusinc/builtin.h:46:                 pow(double, long int)
c:/djgpp/include/math.h:120:                 pow(double, double)
t$1.cc:4: call of overloaded `pow' is ambiguous
c:/djgpp/cplusinc/builtin.h:47: candidates are: pow(long int, long int)
c:/djgpp/cplusinc/builtin.h:46:                 pow(double, long int)
c:/djgpp/include/math.h:120:                 pow(double, double)

  How ever can I get all three of these pow(,) functions current at once?, so
that any call of pow(,) gets the form that needs the least amount of implicit
coercions, like I thought was the rule and the purpose of overloading?
  ............................................
  "He can use `pow' if he wants to, and `eeeeek' amd `zam' and `thud' if he
can find a use for them." (from an article in the Algol Bulletin about how to
represent the power operator) (Algol was a precursor of C).