78 lines
2.3 KiB
Python
78 lines
2.3 KiB
Python
from mpmath import *
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from random import seed, randint, random
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import math
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# Test compatibility with Python floats, which are
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# IEEE doubles (53-bit)
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N = 5000
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seed(1)
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# Choosing exponents between roughly -140, 140 ensures that
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# the Python floats don't overflow or underflow
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xs = [(random()-1) * 10**randint(-140, 140) for x in range(N)]
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ys = [(random()-1) * 10**randint(-140, 140) for x in range(N)]
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# include some equal values
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ys[int(N*0.8):] = xs[int(N*0.8):]
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# Detect whether Python is compiled to use 80-bit floating-point
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# instructions, in which case the double compatibility test breaks
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uses_x87 = -4.1974624032366689e+117 / -8.4657370748010221e-47 \
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== 4.9581771393902231e+163
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def test_double_compatibility():
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mp.prec = 53
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for x, y in zip(xs, ys):
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mpx = mpf(x)
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mpy = mpf(y)
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assert mpf(x) == x
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assert (mpx < mpy) == (x < y)
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assert (mpx > mpy) == (x > y)
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assert (mpx == mpy) == (x == y)
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assert (mpx != mpy) == (x != y)
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assert (mpx <= mpy) == (x <= y)
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assert (mpx >= mpy) == (x >= y)
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assert mpx == mpx
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if uses_x87:
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mp.prec = 64
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a = mpx + mpy
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b = mpx * mpy
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c = mpx / mpy
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d = mpx % mpy
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mp.prec = 53
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assert +a == x + y
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assert +b == x * y
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assert +c == x / y
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assert +d == x % y
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else:
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assert mpx + mpy == x + y
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assert mpx * mpy == x * y
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assert mpx / mpy == x / y
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assert mpx % mpy == x % y
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assert abs(mpx) == abs(x)
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assert mpf(repr(x)) == x
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assert ceil(mpx) == math.ceil(x)
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assert floor(mpx) == math.floor(x)
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def test_sqrt():
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# this fails quite often. it appers to be float
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# that rounds the wrong way, not mpf
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fail = 0
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mp.prec = 53
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for x in xs:
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x = abs(x)
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mp.prec = 100
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mp_high = mpf(x)**0.5
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mp.prec = 53
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mp_low = mpf(x)**0.5
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fp = x**0.5
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assert abs(mp_low-mp_high) <= abs(fp-mp_high)
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fail += mp_low != fp
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assert fail < N/10
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def test_bugs():
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# particular bugs
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assert mpf(4.4408920985006262E-16) < mpf(1.7763568394002505E-15)
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assert mpf(-4.4408920985006262E-16) > mpf(-1.7763568394002505E-15)
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