Profiling example
/* mpfact.c
 *
 * multiple precision factorial computation
 *
 * example for performance analysis of programs
 *
 * TODO: add basic operations mpz_*
 *
 * (c) GPL  due to using GMP
 *
 */
#include <gmp.h> /* use GMP */
#include <stdio.h>
#include <stdlib.h>
#define MAXN 100000L
int main(int argc, char *argv[]) {
    int i;
    long int n;
    mpz_t x;
    if(argc!=2) {
        fprintf(stderr,"Usage: %s number\n", argv[0]);
        return 1;
    }
    n = strtol(argv[1],NULL,10);
    if(n < 0 || n > MAXN) {
        fprintf(stderr,"%s: number out of range (0..%ld)\n", argv[0], MAXN);
        return 1;
    }
    mpz_init_set_ui(x,1);
    for(i=1; i<=n; i++)
        mpz_mul_ui(x,x,i);
    printf("\n%ld! = ", n);
    mpz_out_str(stdout,10,x);
    printf("\n\n");
    return 0;
}
Output
time ./mpfact 5000              GMP
real    0m0.021s
user    0m0.012s
sys     0m0.004s
time ./mpfact- 5000             fgmp
real    0m7.262s
user    0m6.252s
sys     0m0.028s
gprof output (using program linked with fgmp - simple GMP-like library):
Flat profile:
Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total           
 time   seconds   seconds    calls   s/call   s/call  name    
 78.98     12.29    12.29    16326     0.00     0.00  udiv
 12.34     14.21     1.92     5000     0.00     0.00  mpz_mul
  3.98     14.83     0.62    16326     0.00     0.00  urshift
  1.61     15.08     0.25    32652     0.00     0.00  ulshift
  1.09     15.25     0.17   142421     0.00     0.00  _mpz_realloc
  0.90     15.39     0.14    86631     0.00     0.00  mpz_set
  0.90     15.53     0.14    70313     0.00     0.00  digits
  0.19     15.56     0.03   126090     0.00     0.00  mpz_clear
  0.00     15.56     0.00   121092     0.00     0.00  mpz_init
  0.00     15.56     0.00    32654     0.00     0.00  uzero
  0.00     15.56     0.00    16326     0.00     0.00  zero
  0.00     15.56     0.00     5001     0.00     0.00  mpz_init_set_ui
  0.00     15.56     0.00     5000     0.00     0.00  mpz_mul_ui
  0.00     15.56     0.00        2     0.00     0.00  mpz_sizeinbase
  0.00     15.56     0.00        1     0.00    13.62  mpz_get_str
  0.00     15.56     0.00        1     0.00    13.62  mpz_out_str
  0.00     15.56     0.00        1     0.00     0.00  mpz_set_ui
 %         the percentage of the total running time of the
time       program used by this function.
cumulative a running sum of the number of seconds accounted
 seconds   for by this function and those listed above it.
 self      the number of seconds accounted for by this
seconds    function alone.  This is the major sort for this
           listing.
calls      the number of times this function was invoked, if
           this function is profiled, else blank.
 
 self      the average number of milliseconds spent in this
ms/call    function per call, if this function is profiled,
	   else blank.
 total     the average number of milliseconds spent in this
ms/call    function and its descendents per call, if this 
	   function is profiled, else blank.
name       the name of the function.  This is the minor sort
           for this listing. The index shows the location of
	   the function in the gprof listing. If the index is
	   in parenthesis it shows where it would appear in
	   the gprof listing if it were to be printed.
		     Call graph (explanation follows)
granularity: each sample hit covers 4 byte(s) for 0.06% of 15.56 seconds
index % time    self  children    called     name
                                                 
[1]    100.0    0.00   15.56                 main [1]
                0.00   13.62       1/1           mpz_out_str [2]
                0.00    1.94    5000/5000        mpz_mul_ui [5]
                0.00    0.00       1/5001        mpz_init_set_ui [17]
-----------------------------------------------
                0.00   13.62       1/1           main [1]
[2]     87.5    0.00   13.62       1         mpz_out_str [2]
                0.00   13.62       1/1           mpz_get_str [3]
                0.00    0.00       1/2           mpz_sizeinbase [13]
-----------------------------------------------
                0.00   13.62       1/1           mpz_out_str [2]
[3]     87.5    0.00   13.62       1         mpz_get_str [3]
               12.29    1.33   16326/16326       udiv [4]
                0.00    0.00       1/86631       mpz_set [9]
                0.00    0.00       1/2           mpz_sizeinbase [13]
                0.00    0.00       2/126090      mpz_clear [12]
                0.00    0.00   16328/32654       uzero [15]
                0.00    0.00       4/121092      mpz_init [14]
                0.00    0.00       1/1           mpz_set_ui [18]
-----------------------------------------------
               12.29    1.33   16326/16326       mpz_get_str [3]
[4]     87.5   12.29    1.33   16326         udiv [4]
                0.62    0.07   16326/16326       urshift [7]
                0.25    0.15   32652/32652       ulshift [8]
                0.05    0.05   32652/86631       mpz_set [9]
                0.07    0.00   32652/70313       digits [11]
                0.06    0.00   48978/142421      _mpz_realloc [10]
                0.02    0.00   65304/126090      mpz_clear [12]
                0.00    0.00   65304/121092      mpz_init [14]
                0.00    0.00   16326/32654       uzero [15]
                0.00    0.00   16326/16326       zero [16]
-----------------------------------------------
                0.00    1.94    5000/5000        main [1]
[5]     12.5    0.00    1.94    5000         mpz_mul_ui [5]
                1.92    0.02    5000/5000        mpz_mul [6]
                0.00    0.00    5000/126090      mpz_clear [12]
                0.00    0.00    5000/5001        mpz_init_set_ui [17]
-----------------------------------------------
                1.92    0.02    5000/5000        mpz_mul_ui [5]
[6]     12.5    1.92    0.02    5000         mpz_mul [6]
                0.01    0.01    5000/86631       mpz_set [9]
                0.01    0.00    5000/142421      _mpz_realloc [10]
                0.00    0.00    5000/126090      mpz_clear [12]
                0.00    0.00    5000/121092      mpz_init [14]
-----------------------------------------------
                0.62    0.07   16326/16326       udiv [4]
[7]      4.5    0.62    0.07   16326         urshift [7]
                0.03    0.02   16326/86631       mpz_set [9]
                0.02    0.00   16326/142421      _mpz_realloc [10]
                0.00    0.00   16326/126090      mpz_clear [12]
                0.00    0.00   16326/121092      mpz_init [14]
-----------------------------------------------
                0.25    0.15   32652/32652       udiv [4]
[8]      2.5    0.25    0.15   32652         ulshift [8]
                0.05    0.05   32652/86631       mpz_set [9]
                0.04    0.00   32652/142421      _mpz_realloc [10]
                0.01    0.00   32652/126090      mpz_clear [12]
                0.00    0.00   32652/121092      mpz_init [14]
-----------------------------------------------
                0.00    0.00       1/86631       mpz_get_str [3]
                0.01    0.01    5000/86631       mpz_mul [6]
                0.03    0.02   16326/86631       urshift [7]
                0.05    0.05   32652/86631       ulshift [8]
                0.05    0.05   32652/86631       udiv [4]
[9]      1.7    0.14    0.12   86631         mpz_set [9]
                0.07    0.00   37659/70313       digits [11]
                0.05    0.00   39465/142421      _mpz_realloc [10]
                0.00    0.00    1806/126090      mpz_clear [12]
                0.00    0.00    1806/121092      mpz_init [14]
-----------------------------------------------
                0.01    0.00    5000/142421      mpz_mul [6]
                0.02    0.00   16326/142421      urshift [7]
                0.04    0.00   32652/142421      ulshift [8]
                0.05    0.00   39465/142421      mpz_set [9]
                0.06    0.00   48978/142421      udiv [4]
[10]     1.1    0.17    0.00  142421         _mpz_realloc [10]
-----------------------------------------------
                0.00    0.00       2/70313       mpz_sizeinbase [13]
                0.07    0.00   32652/70313       udiv [4]
                0.07    0.00   37659/70313       mpz_set [9]
[11]     0.9    0.14    0.00   70313         digits [11]
-----------------------------------------------
                0.00    0.00       2/126090      mpz_get_str [3]
                0.00    0.00    1806/126090      mpz_set [9]
                0.00    0.00    5000/126090      mpz_mul [6]
                0.00    0.00    5000/126090      mpz_mul_ui [5]
                0.00    0.00   16326/126090      urshift [7]
                0.01    0.00   32652/126090      ulshift [8]
                0.02    0.00   65304/126090      udiv [4]
[12]     0.2    0.03    0.00  126090         mpz_clear [12]
-----------------------------------------------
                0.00    0.00       1/2           mpz_get_str [3]
                0.00    0.00       1/2           mpz_out_str [2]
[13]     0.0    0.00    0.00       2         mpz_sizeinbase [13]
                0.00    0.00       2/70313       digits [11]
-----------------------------------------------
                0.00    0.00       4/121092      mpz_get_str [3]
                0.00    0.00    1806/121092      mpz_set [9]
                0.00    0.00    5000/121092      mpz_mul [6]
                0.00    0.00   16326/121092      urshift [7]
                0.00    0.00   32652/121092      ulshift [8]
                0.00    0.00   65304/121092      udiv [4]
[14]     0.0    0.00    0.00  121092         mpz_init [14]
-----------------------------------------------
                0.00    0.00   16326/32654       udiv [4]
                0.00    0.00   16328/32654       mpz_get_str [3]
[15]     0.0    0.00    0.00   32654         uzero [15]
-----------------------------------------------
                0.00    0.00   16326/16326       udiv [4]
[16]     0.0    0.00    0.00   16326         zero [16]
-----------------------------------------------
                0.00    0.00       1/5001        main [1]
                0.00    0.00    5000/5001        mpz_mul_ui [5]
[17]     0.0    0.00    0.00    5001         mpz_init_set_ui [17]
-----------------------------------------------
                0.00    0.00       1/1           mpz_get_str [3]
[18]     0.0    0.00    0.00       1         mpz_set_ui [18]
-----------------------------------------------
 This table describes the call tree of the program, and was sorted by
 the total amount of time spent in each function and its children.
 Each entry in this table consists of several lines.  The line with the
 index number at the left hand margin lists the current function.
 The lines above it list the functions that called this function,
 and the lines below it list the functions this one called.
 This line lists:
     index	A unique number given to each element of the table.
		Index numbers are sorted numerically.
		The index number is printed next to every function name so
		it is easier to look up where the function in the table.
     % time	This is the percentage of the `total' time that was spent
		in this function and its children.  Note that due to
		different viewpoints, functions excluded by options, etc,
		these numbers will NOT add up to 100%.
     self	This is the total amount of time spent in this function.
     children	This is the total amount of time propagated into this
		function by its children.
     called	This is the number of times the function was called.
		If the function called itself recursively, the number
		only includes non-recursive calls, and is followed by
		a `+' and the number of recursive calls.
     name	The name of the current function.  The index number is
		printed after it.  If the function is a member of a
		cycle, the cycle number is printed between the
		function's name and the index number.
 For the function's parents, the fields have the following meanings:
     self	This is the amount of time that was propagated directly
		from the function into this parent.
     children	This is the amount of time that was propagated from
		the function's children into this parent.
     called	This is the number of times this parent called the
		function `/' the total number of times the function
		was called.  Recursive calls to the function are not
		included in the number after the `/'.
     name	This is the name of the parent.  The parent's index
		number is printed after it.  If the parent is a
		member of a cycle, the cycle number is printed between
		the name and the index number.
 If the parents of the function cannot be determined, the word
 `' is printed in the `name' field, and all the other
 fields are blank.
 For the function's children, the fields have the following meanings:
     self	This is the amount of time that was propagated directly
		from the child into the function.
     children	This is the amount of time that was propagated from the
		child's children to the function.
     called	This is the number of times the function called
		this child `/' the total number of times the child
		was called.  Recursive calls by the child are not
		listed in the number after the `/'.
     name	This is the name of the child.  The child's index
		number is printed after it.  If the child is a
		member of a cycle, the cycle number is printed
		between the name and the index number.
 If there are any cycles (circles) in the call graph, there is an
 entry for the cycle-as-a-whole.  This entry shows who called the
 cycle (as parents) and the members of the cycle (as children.)
 The `+' recursive calls entry shows the number of function calls that
 were internal to the cycle, and the calls entry for each member shows,
 for that member, how many times it was called from other members of
 the cycle.
Index by function name
  [10] _mpz_realloc            [6] mpz_mul                 [4] udiv (gmp.c)
  [11] digits (gmp.c)          [5] mpz_mul_ui              [8] ulshift (gmp.c)
  [12] mpz_clear               [2] mpz_out_str             [7] urshift (gmp.c)
   [3] mpz_get_str             [9] mpz_set                [15] uzero (gmp.c)
  [14] mpz_init               [18] mpz_set_ui             [16] zero (gmp.c)
  [17] mpz_init_set_ui        [13] mpz_sizeinbase