blob: 601063d4248f47858f51d854de627d70c307bbe0 [file] [log] [blame]
 #!/usr/bin/env python # Compute 10 ** exp with exp in the range [min_exponent, max_exponent] and print # normalized (with most-significant bit equal to 1) significands in hexadecimal. from __future__ import print_function min_exponent = -348 max_exponent = 340 step = 8 significand_size = 64 exp_offset = 2000 class fp: pass powers = [] for i, exp in enumerate(range(min_exponent, max_exponent + 1, step)): result = fp() n = 10 ** exp if exp >= 0 else 2 ** exp_offset / 10 ** -exp k = significand_size + 1 # Convert to binary and round. binary = '{:b}'.format(n) result.f = (int('{:0<{}}'.format(binary[:k], k), 2) + 1) / 2 result.e = len(binary) - (exp_offset if exp < 0 else 0) - significand_size powers.append(result) # Sanity check. exp_offset10 = 400 actual = result.f * 10 ** exp_offset10 if result.e > 0: actual *= 2 ** result.e else: for j in range(-result.e): actual /= 2 expected = 10 ** (exp_offset10 + exp) precision = len('{}'.format(expected)) - len('{}'.format(actual - expected)) if precision < 19: print('low precision:', precision) exit(1) print('Significands:', end='') for i, fp in enumerate(powers): if i % 3 == 0: print(end='\n ') print(' {:0<#16x}'.format(fp.f, ), end=',') print('\n\nExponents:', end='') for i, fp in enumerate(powers): if i % 11 == 0: print(end='\n ') print(' {:5}'.format(fp.e), end=',') print('\n\nMax exponent difference:', max([x.e - powers[i - 1].e for i, x in enumerate(powers)][1:]))