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Short-circuit return on zero input in cyl_bessel_y() #71

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Short-circuit return on zero input in cyl_bessel_y() #71

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1ec331f
Short-circuit return on zero input in cyl_bessel_y()
WarrenWeckesser Oct 30, 2025
9b37f38
Fix sign of INFINITY.
WarrenWeckesser Oct 30, 2025
dc432e3
Fix whitespace.
WarrenWeckesser Oct 30, 2025
0f94f16
Fix sign of INFINITY when v < 0 and z = 0
WarrenWeckesser Oct 30, 2025
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25 changes: 24 additions & 1 deletion include/xsf/bessel.h
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Original file line number Diff line number Diff line change
Expand Up @@ -945,9 +945,32 @@ inline std::complex<double> cyl_bessel_y(double v, std::complex<double> z) {

if (z.real() == 0 && z.imag() == 0) {
/* overflow */
cy_y.real(-INFINITY);
double re;
if (sign == 1 || v < 0.5) {
re = -INFINITY;
} else {
if (v >= std::pow(2.0, 53)) {
// The original v (before sign flip) is an even negative integer.
re = -INFINITY;
} else {
double s = v - 0.5;
if (s != v && std::rint(s) == s) {
re = 0.0;
} else {
double si = std::floor(s);
double half_si = si / 2;
if (std::floor(half_si) == half_si) {
re = INFINITY;
} else {
re = -INFINITY;
}
}
}
}
cy_y.real(re);
cy_y.imag(0);
set_error("yv", SF_ERROR_OVERFLOW, NULL);
return cy_y;
} else {
nz = amos::besy(z, v, kode, n, &cy_y, &ierr);
set_error_and_nan("yv:", ierr_to_sferr(nz, ierr), cy_y);
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