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gmp

simple GMP/MPIR questions

I'm trying out GMP/MPIR with VS 2010, I don't understand why the output is 0.999999999999999999909e101 for input 10 10.

I'd expect all the digits to show because i put 1000 for n_digits in mpf_out_str call, using 0 same result. And why the 9's, and 909e101?

Also how would you input huge numbers, gmp_scanf doesn't seem to handle 100's of digits.

#include <mpirxx.h>

main()
{

  mpf_t tt, t2;

  mpf_init(tt);
  mpf_init(t2);

  gmp_scanf("%Fe\n", tt);
  gmp_scanf("%Fe\n", t2);

  for (int i = 0; i < 100; i++)
      mpf_mul(tt, tt, t2);

  mpf_out_str(stdout, 10, 1000, tt);

  mpf_clear(tt);
  mpf_clear(t2);

  getc(stdin); 

}
Solution

  • You need to specify the precision of an mpf_t. See mpf_init2() and mpf_set_default_prec().