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Comment by edoloughlin | Hacker News Reader

Lost me a bit at

  Im(f(x+ih))/h

near the end (that's a fancy I that android FF won't paste). Can anyone explain where 'm' came from?

Or is 'Im' just a fn returning the imaginary part of its argument?

EDIT: reading the code following, it's clear that Im is just that.

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I was also lost at that part, although for a different reason. The function f was assumed to be from R to R, so it does not make formal sense to plug in f(x+ih).

I guess the author has the unstated assumption that f is the restriction to R of a function on C.

Great point, and I apologize for the confusion. The function should be C to C, with the added restriction of R to R.

Thanks, I just realized that when I introduced the notation above, I just used I(f), but then when I used it below I wrote Im(f). I will clear that up.

Im is for imaginary part of its argument as you say

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