complex op• 数据种类:cpoints → measurement
• 调用:import mathops; mathops.cplx_winding_number(z, w=0.0)(或 opsmath.get("cplx_winding_number"))
闭合围道绕某点的卷绕数(回转数)。
> 以下的详细说明为原文 —— 摘要与标题已翻译。
How many times the polygon `z` (closing segment implicit) travels
counter-clockwise around *w*: `+1` for a simple positively-oriented loop
containing it, `-1 clockwise, 0 outside, ±k for a k`-fold
loop. Computed as the sum of the principal-value argument increments of
`z_k - w divided by 2*pi` and rounded — for a *polygon* that sum is an
exact multiple of `2*pi`, so the result is an exact integer, not an
estimate (the rounding merely removes ~1e-14 of accumulated float error).
Honest limitation — **the count can alias low, and no local check can stop
it**: this is the winding number of the polygon *through the samples*,
which equals that of the underlying curve only if the sampling resolves it.
A segment that turns the ray to *w* by `>= pi` is ambiguous (which side
did it pass?) and raises. Below that there is no contradiction to detect:
`z**5 sampled on a 4-point circle turns exactly pi/2` per step and
counts 1 instead of 5 (measured). From `pi/2` up, a
`RuntimeWarning says so (WIND_ALIAS_WARN`); the only real remedy is
the classical one — refine until the count stops changing.
Raises `ValueError`: *w* coincides with a vertex or lies on a segment
(the winding number is undefined on the contour), a segment subtends
`>= pi` as seen from *w* (undersampled — refine the contour), fewer than
3 points, degenerate contour, non-finite/masked input.
HALCON: no operator (`test_region_point` answers the related but weaker
inside/outside question for regions).
mathops 的每个算子都先校验输入再计算(不让任何东西无声通过):
• **complex 输入一律 ValueError** —— 强制转成 float64 会无声丢掉虚部(numpy 只发一个 ComplexWarning,然后返回一个「看着合理却是错的」实数)。请显式写出 .real/.imag/abs(),或改用支持复数的 complexops。
• **含被掩元素的 masked array 一律 ValueError** —— 拒绝「剥掉掩码直接使用下面原值」的隐式转换。请显式选择填充还是丢弃。
• **所有输入中的 NaN/Inf 一律 ValueError**(明确给出个数后拒绝 —— 它会污染整个结果)。
• 形状严格:不对 1-D 与 2-D 做隐式提升或广播(向量槽位收到矩阵、矩阵槽位收到向量都是 ValueError;请显式 reshape)。
• 尺寸上限:接受矩阵的算子与 stat_histogram 的 bins,超过 mathops.MAX_ELEMENTS(2^26 ≈ 6700 万个元素)即 ValueError。
• 示例数据目录(下载 URL / 许可证) —— 2-D 用 skimage.data(BSD/公有领域)加合成图,3-D 给出真实数据源(Stanford/PDS 等)的下载 URL。
• 算子来历与参考文献 —— 该算子族所依据的研究/方法出处。
• 算法的正典(作者・年份)与用途见上面的族使用指南。
• math_complex — py -3.11 examples/math_complex.py
measurement 作为输入)—
complex)cplx_contour_circle · cplx_poly_eval · cplx_contour_integral · cplx_cauchy_value · cplx_argument_principle · cplx_laurent_coeffs · cplx_joukowski · cplx_mobius
*Provenance: mathops.py — MATH 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.