21 lines
634 B
Scheme
21 lines
634 B
Scheme
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;; Break a positive real number down to a normalized mantissa and
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;; exponent. Default base=2, mant-size=52, exp-size=11 for IEEE doubles.
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(define mantissa+exponent
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(case-lambda
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[(num) (mantissa+exponent num 2)]
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[(num base) (mantissa+exponent num base 52)]
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[(num base mant-size) (mantissa+exponent num base mant-size 11)]
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[(num base mant-size exp-size)
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(if (zero? num)
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(list 0 0)
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(let* ((bot (expt base mant-size))
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(top (* base bot)))
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(let lp ((n num) (e 0))
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(cond
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((>= n top) (lp (quotient n base) (+ e 1)))
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((< n bot) (lp (* n base) (- e 1)))
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(else (list n e))))))]))
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