math.h issues

[Charles G Waldman]

The 11th Angel writes:
 > I've been having problems trying to use the sqrt() and log() functions
 > under glibc 2.2.1 with gcc 2.95.2 and 2.95.3.  The manpages say those
 > functions are part of math.h, which they are not.

math.h only provides the function prototypes (i.e. declarations of the
type of the function's return value and arguments).  To get the actual
symbol definitions you have to link your program with the -lm flag, to
instruct the linker to link in the math library (libm.so).