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This patch improves parsing of floating point numbers by converting all the digits (integer and fractional) together into a number 1 or greater, and then applying the correct power of 10 at the very end. In particular the multiple "multiply by 0.1" operations to build a fraction are now combined together and applied at the same time as the exponent, at the very end. This helps to retain precision during parsing of floats, and also includes a check that the number doesn't overflow during the parsing. One benefit is that a float will have the same value no matter where the decimal point is located, eg 1.23 == 123e-2.
23 lines
723 B
Python
23 lines
723 B
Python
# test parsing of floats
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inf = float('inf')
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# it shouldn't matter where the decimal point is if the exponent balances the value
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print(float('1234') - float('0.1234e4'))
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print(float('1.015625') - float('1015625e-6'))
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# very large integer part with a very negative exponent should cancel out
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print(float('9' * 60 + 'e-60'))
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print(float('9' * 60 + 'e-40'))
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print(float('9' * 60 + 'e-20') == float('1e40'))
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# many fractional digits
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print(float('.' + '9' * 70))
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print(float('.' + '9' * 70 + 'e20'))
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print(float('.' + '9' * 70 + 'e-50') == float('1e-50'))
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# tiny fraction with large exponent
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print(float('.' + '0' * 60 + '1e10') == float('1e-51'))
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print(float('.' + '0' * 60 + '9e25'))
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print(float('.' + '0' * 60 + '9e40'))
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