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cls/derivative.sml

Created May 12, 2018 16:02
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Derivative of a function in Standard ML, using Real.nextAfter
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derivative.sml
fun derivative (f : real -> real) (x : real) : real =
let val pos = Real.nextAfter (x, Real.posInf)
val neg = Real.nextAfter (x, Real.negInf)
in
(f pos - f neg) / (pos - neg)
end
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cls commented May 12, 2018

I'm unsure if Standard ML guarantees that pos - neg here be non-zero.

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