/*
 * ISA 563, Spring 2011
 * Copyleft by Muhammad Abdulla
 */


#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <dlfcn.h>

/*
 * dynmath.c -- demonstrates dynamic loading of library functions 
 */

int main(int argc, char **argv) {
    void *handle;
    double (*cosine)(double);
    double (*sine)(double);
    char *error;

    char *libpath = "/lib/libm.so.6";
    double angle = M_PI / 3;

    if ( argc > 1 ) {
       libpath = argv[1];
    }

    if ( argc > 2 ) {
       angle = atof(argv[2]);
    }

    handle = dlopen (libpath, RTLD_LAZY);
    if (!handle) {
        fputs (dlerror(), stderr);
        exit(1);
    }

    cosine = dlsym(handle, "cos");
    if ((error = dlerror()) != NULL)  {
        fputs(error, stderr);
        exit(1);
    }

    sine = dlsym(handle, "sin");
    if ((error = dlerror()) != NULL)  {
        fputs(error, stderr);
        exit(1);
    }

    printf ("sin(%g) = %g\n", angle, (*sine)(angle));
    printf ("cos(%g) = %g\n", angle, (*cosine)(angle));

    dlclose(handle);
}