How to invoke math functions from dbx?

Question

Is there an easy way to invoke math functions from dbx? If I try, for example, to call sqrt I get meaningless results:
(dbx) print sqrt(4.0)
sqrt(4) = 1074790400
(dbx)
This is from code which uses sqrt, so sqrt should be accessible. Does this need some kind of cast?

Answer 1

It turns out that this is a bit different than it looks: dbx is indeed able to invoke functions invoked in this way correctly; dbx just fails to print a sensible return value.
I tried with the following small function:
#include <stdio.h>
int printme(double x) {
printf("This is %g\n",x);
return (int)2*x;
Compiling this without -g, linking this with some hello world program and invoking the function from dbx gives
(dbx) print ((int (*)(double))printme)(4.0)
This is 4
((int (*)(double)) printme)(4) = &(noname)(double) at 0x8
(dbx)
The line "This is 4" clearly indicates that the function has been invoked correctly. Just the printed return value is meaningless. In this case, it is even possible to construct expressions with the return value:
(dbx) print 5 + ((int (*)(double))printme)(4.0)
This is 4
5+((int (*)(double)) printme)(4) = 13
i.e. dbx "knows" the correct return value 8. This does, however, apparently not work with return values of type double (i.e. in the original sqrt-Example).
I have therefore submitted a bug report with bugs.sun.com; I will post the BugID when (and if) this has been accepted.