FLINT3.7.0-dev
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ca_csgn

Synopsis#include <flint/ca.h>
void ca_csgn(ca_t res, const ca_t x, ca_ctx_t ctx)source

Sets res to the extension of the real sign function that is 1 in the open right half-plane, −1-1 in the open left half-plane, and the sign of the imaginary part on the imaginary axis; equivalently csgn⁡(z)=z/z2\operatorname{csgn}(z) = z / \sqrt{z^2} for z≠0z \ne 0, and csgn⁡(0)=0\operatorname{csgn}(0) = 0. For a signed infinity csgn⁡(c∞)=csgn⁡(c)\operatorname{csgn}(c \infty) = \operatorname{csgn}(c); unsigned infinity gives Undefined. The result is Unknown when the required sign tests fail.

Cite this page

The FLINT team, “ca_csgn (ca.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/ca/ca_csgn.html (generated 2026-11-02).