Ciao, Il Mar, 18 Giugno 2013 5:03 am, hai scritto: > I need have 30 decimal point,but when it use the float division of gmp,the You need 30 decimal digits. Did you set "precision" to _at_least_ log_2(10)*30 ~= 100 bits? Look at http://gmplib.org/manual/Initializing-Floats.html#Initializing-Floats Regards, m -- http://bodrato.it/papers/