Re: sqrt C function

[Paul Scott <waterhorse@ultrasw.com>]

R1nso13@aol.com wrote:

> when i try to use the sqrt function in gcc 3.0, and the gcc that's standard 
> with 2.2r3 ( i forget the version)  i get errors. here's some example code:
>
> #include <math.h>
> #include <stdio.h>
>
> double num;
> double num_root;
>
> int main ()
> {
>     num = 4;
>     num_root = sqrt(num);
>     return (0);
> }
>
> fails to compile. i've tried using double as well as float variables. i'm 
> sure this is due to poor coding, but i'm looked at the man page and 
> linuxdoc.org and cannot find any example implementations of sqrt(). I'm 
> running i386 arch, and have math.h (as well as the complete gcc 3.0) 
> installed.


I doubt if this is your problem but on most compilers:

    double num;

    num = 4;

is inefficient;  It normally causes an integer constant 4 to be stored 
somewhere.  Then when num = 4;  is executed the integer 4 is converted 
to double every you execute the code.

    num = 4.;

is the normal way but you could even do use num = 4.L;  in this case to 
cause all of the conversion to occur at compile time.

Paul Scott