Sorry for posting two messages, but the last mail was not complete. Here is whats missing: I have the following problems with the current code: 1) if precision is set to 9999999 (7 nines) the multiplication needs 0.4 seconds. However if I set the precision to 9999999 (7 nines) the function needs 5,4 seconds. 2) if I generate a number which is 100000 digits long, then the problem crashes when it executes mpf_init_set_str(x, createStringDecimal(100000), 0); However with 10000 digits it works fast and fine: mpf_init_set_str(x, createStringDecimal(10000), 0); what am I doing wrong ? hope you can help. also, how I measure the elapsed time in milliseconds ? thank you in advance, Andreas <div class="gmail_quote">On Dec 14, 2007 9:47 PM, Andreas Andreakis <<a href="mailto:andreas.andreakis@googlemail.com">andreas.andreakis@googlemail.com</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hallo, I´m currently evaluating GMP against libraries from other languages (such as from java). I´ve already tried to write a program which multiplies two numbers, but I´m experiencing various problems. Also I´m not very experienced in C++, so I cant tell if its me if I´m using GMP wrong. Thus I need your help, in order to make sure that my function is written correctly and as efficient as possible. This are the conditions: 1) precision must be presetup and set to 999999999 2) generate a decimal from a string := number (I hava already the method which generates the string / const char) 3) calculate number*number 4) show elapsed time in milliseconds for that operation Here is my code (using C): int main() {         long precision = 9999999;     mpf_set_default_prec(precision);     mpf_t x, result;         mpf_init(result);     mpf_init_set_str(x, createStringDecimal(10000), 0);  //createStringDecimal is already implemented, it returns a floating point number of the given length     clock_t t1, t2;     t1 = clock();        //action     mpf_mul(result, x, x);         t2 = clock();     printf("\nFinished in %.2f seconds.\n\n", (t2-t1)*1.0/CLOCKS_PER_SEC);     int n = 1000;     gmp_printf ("fixed point mpf %.*Ff with %d digits\n", n, x, n);     gmp_printf ("fixed point mpf %.*Ff with %d digits\n", n, result, n);         return 0; } </blockquote></div>