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fix bugs in unwrap function #16977

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fix bugs in unwrap function #16977

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6 changes: 3 additions & 3 deletions numpy/lib/function_base.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1537,10 +1537,10 @@ def unwrap(p, discont=pi, axis=-1):
slice1 = [slice(None, None)]*nd # full slices
slice1[axis] = slice(1, None)
slice1 = tuple(slice1)
ddmod = mod(dd + pi, 2*pi) - pi
_nx.copyto(ddmod, pi, where=(ddmod == -pi) & (dd > 0))
ddmod = mod(dd + discont, 2 * discont) - discont
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@eric-wieser eric-wieser Aug 1, 2020 •
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This 2*pi change is definitely incorrect - the docs refer specifically to comparing discont to pi and 2*pi, but after this change the function does not mention pi at all.

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Yes, absolutely true, the meaning of discont was misused here. But the logic is correct. I will correct this. I would propose a name like ´interval_sizesincemin_valandmax_val` from #14877 don't make sense at all. It only corrects differences, so it will do the same correction for

unwrap([ 1, 2, 3, 4, 5, 6, 1, 2, 3], min_val=1, max_val=7)

as for

unwrap([ 1, 2, 3, 4, 5, 6, 1, 2, 3], min_val=0, max_val=6)

. Only the difference max_val - min_val matters.

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since min_valandmax_val from #14877 don't make sense at all.

I don't agree with that - they makes sense to me, and should satisfy unwrap(arr, min=-a, max=a) + b== unwrap(arr + b, min=-a + b, max=a + b)

_nx.copyto(ddmod, discont, where=(ddmod == -discont) & (dd > 0))
ph_correct = ddmod - dd
_nx.copyto(ph_correct, 0, where=abs(dd) < discont)
_nx.copyto(ph_correct, 0, where=abs(dd) < discont * 1.5)
up = array(p, copy=True, dtype='d')
up[slice1] = p[slice1] + ph_correct.cumsum(axis)
return up
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