About log() in GCC

[JN_Lin at utc dot com dot tw]

Dear :
When I want to use "log" in my program, I must include the header
file math.h.  But when I compiler my program ,some message showing  as
following:

    Undefined                       first referenced
    symbol                             in file
    log                                 /var/tmp/cca0060l1.o
    ld: fatal: Symbol referencing errors. No output written to a.out


My compiler command:
       gcc 1.c

My program:
    #include <stdio.h>
    #include <math.h>
    void main()
    {
         double x = 100;
         printf("Var=%f \n" , log(x)) ;
    }

Patrick-Lin
Thanks