iframe-proxy | Sunbelt Computer Software

History

73 lines (65 loc) · 2.38 KB

Raw

# Test accuracy of `repr` conversions.

# This test also increases code coverage for corner cases.

try:

import array, math, random

except ImportError:

print("SKIP")

raise SystemExit

# The largest errors come from seldom used very small numbers, near the

# limit of the representation. So we keep them out of this test to keep

# the max relative error display useful.

if float("1e-100") == 0.0:

# single-precision

float_type = "f"

float_size = 4

# testing range

min_expo = -96 # i.e. not smaller than 1.0e-29

# Expected results (given >=50'000 samples):

# - MICROPY_FLTCONV_IMPL_EXACT: 100% exact conversions

# - MICROPY_FLTCONV_IMPL_APPROX: >=98.53% exact conversions, max relative error <= 1.01e-7

min_success = 0.980 # with only 1200 samples, the success rate is lower

max_rel_err = 1.1e-7

# REPR_C is typically used with FORMAT_IMPL_BASIC, which has a larger error

is_REPR_C = float("1.0000001") == float("1.0")

if is_REPR_C: # REPR_C

min_success = 0.83

max_rel_err = 5.75e-07

else:

# double-precision

float_type = "d"

float_size = 8

# testing range

min_expo = -845 # i.e. not smaller than 1.0e-254

# Expected results (given >=200'000 samples):

# - MICROPY_FLTCONV_IMPL_EXACT: 100% exact conversions

# - MICROPY_FLTCONV_IMPL_APPROX: >=99.83% exact conversions, max relative error <= 2.7e-16

min_success = 0.997 # with only 1200 samples, the success rate is lower

max_rel_err = 2.7e-16

# Deterministic pseudorandom generator. Designed to be uniform

# on mantissa values and exponents, not on the represented number

def pseudo_randfloat():

rnd_buff = bytearray(float_size)

for _ in range(float_size):

rnd_buff[_] = random.getrandbits(8)

return array.array(float_type, rnd_buff)[0]

random.seed(42)

stats = 0

N = 1200

max_err = 0

for _ in range(N):

f = pseudo_randfloat()

while type(f) is not float or math.isinf(f) or math.isnan(f) or math.frexp(f)[1] <= min_expo:

f = pseudo_randfloat()

str_f = repr(f)

f2 = float(str_f)

if f2 == f:

stats += 1

else:

error = abs((f2 - f) / f)

if max_err < error:

max_err = error

print(N, "values converted")

if stats / N >= min_success and max_err <= max_rel_err:

print("float format accuracy OK")

else:

print("FAILED: repr rate=%.3f%% max_err=%.3e" % (100 * stats / N, max_err))

Sunbelt Computer Software

PL/B Language Development and Support

Navigation Menu

Sunbelt Computer Software

PL/B Language Development and Support

FilesExpand file tree

float_format_accuracy.py

Latest commit

History

float_format_accuracy.py

File metadata and controls