Re: another conditional breakpoint question

[Daniel Jacobowitz <drow@mvista.com>]

On Fri, Sep 20, 2002 at 01:13:04PM -0700, Peter Jay Salzman wrote:
> in the program:
> 
>    #include <math.h>
>    int main(void)
>    {
>         double i = 0.0;
>         double j = cos(i);
>         return 0;
>    }
> 
> i set a breakpoint which should never be reached:
> 
> p@satan% gdb mymath
> (gdb) break main if cos(0.0) > 1000.0
> Breakpoint 1 at 0x8048426: file mymath.c, line 5.
> 
> (gdb) run
> Breakpoint 1, main () at mymath.c:5
> 5               double i = 0.0;
> 
> considering that cosine should be greater than 1 for a real variable,
> this is quite strange!
> 
> 
> i don't know if this is related, but i notice that cos(0) doesn't have a
> value of 1.0.  not even close:
> 
>    (gdb) p cos(0)
>    $3 = 14368
> 
> but just in case gdb doesn't know that cos() returns a double, i also
> tried:
> 
>    (gdb) p/f cos(0.0)
>    $1 = 2.00890148e-41
> 
> neither of these are even close to being right.
> 
> 
> can someone tell me why gdb is reaching that breakpoint which should
> never be reaced?  and is there any way of getting gdb to tell me that
> cos(0) is supposed to be equal to 1?   :*)

You don't have debug information in your libraries.  Try:

(gdb) ptype cos

to see what I mean.  You need debugging info if you want that to wokr.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer