51 lines
1.6 KiB
Python
51 lines
1.6 KiB
Python
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from itertools import product
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from sympy.core.singleton import S
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from sympy.core.symbol import symbols
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from sympy.functions.elementary.exponential import (exp, log)
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from sympy.printing.repr import srepr
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from sympy.codegen.numpy_nodes import logaddexp, logaddexp2
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x, y, z = symbols('x y z')
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def test_logaddexp():
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lae_xy = logaddexp(x, y)
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ref_xy = log(exp(x) + exp(y))
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for wrt, deriv_order in product([x, y, z], range(3)):
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assert (
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lae_xy.diff(wrt, deriv_order) -
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ref_xy.diff(wrt, deriv_order)
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).rewrite(log).simplify() == 0
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one_third_e = 1*exp(1)/3
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two_thirds_e = 2*exp(1)/3
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logThirdE = log(one_third_e)
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logTwoThirdsE = log(two_thirds_e)
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lae_sum_to_e = logaddexp(logThirdE, logTwoThirdsE)
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assert lae_sum_to_e.rewrite(log) == 1
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assert lae_sum_to_e.simplify() == 1
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was = logaddexp(2, 3)
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assert srepr(was) == srepr(was.simplify()) # cannot simplify with 2, 3
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def test_logaddexp2():
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lae2_xy = logaddexp2(x, y)
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ref2_xy = log(2**x + 2**y)/log(2)
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for wrt, deriv_order in product([x, y, z], range(3)):
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assert (
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lae2_xy.diff(wrt, deriv_order) -
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ref2_xy.diff(wrt, deriv_order)
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).rewrite(log).cancel() == 0
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def lb(x):
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return log(x)/log(2)
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two_thirds = S.One*2/3
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four_thirds = 2*two_thirds
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lbTwoThirds = lb(two_thirds)
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lbFourThirds = lb(four_thirds)
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lae2_sum_to_2 = logaddexp2(lbTwoThirds, lbFourThirds)
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assert lae2_sum_to_2.rewrite(log) == 1
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assert lae2_sum_to_2.simplify() == 1
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was = logaddexp2(x, y)
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assert srepr(was) == srepr(was.simplify()) # cannot simplify with x, y
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