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Fix issue #10491 Complex!float.abs / hypot invalid result when argument is small (#10679)

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Aditya Chincholkar 2025-03-17 19:48:39 +05:30 • committed by GitHub
parent fd4979ab99
commit e1d9d0208b
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1 changed files with 56 additions and 5 deletions
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61
std/complex.d
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@ -749,13 +749,42 @@ if (is(T R == Complex!R))
/**
Params: z = A complex number.
Returns: The absolute value (or modulus) of `z`.
*/
* Calculates the absolute value (or modulus) of a complex number.
*
* $(TABLE_SV
* $(TR $(TH $(I z)) $(TH abs(z)) $(TH Notes))
* $(TR $(TD (0, 0)) $(TD 0) $(TD ))
* $(TR $(TD (NaN, any) or (any, NaN)) $(TD NaN) $(TD ))
* $(TR $(TD (Inf, any) or (any, Inf)) $(TD Inf) $(TD ))
* $(TR $(TD (a, b)) normal case $(TD hypot(a, b)) $(TD Uses algorithm to prevent overflow/underflow ))
* )
*
* Params:
* z = A complex number of type Complex!T
*
* Returns:
* The absolute value (modulus) of `z`
*/
T abs(T)(Complex!T z) @safe pure nothrow @nogc
{
import std.math.algebraic : hypot;
return hypot(z.re, z.im);
import std.math.algebraic : sqrt;
import std.math.traits : isInfinity, isNaN;
import std.math : fabs;
import std.algorithm.comparison : max;
if (isNaN(z.re) || isNaN(z.im))
return T.nan;
if (isInfinity(z.re) || isInfinity(z.im))
return T.infinity;
const T maxabs = max(fabs(z.re), fabs(z.im));
if (maxabs == 0.0)
return maxabs;
const T qx = z.re / maxabs;
const T qy = z.im / maxabs;
return maxabs * sqrt(qx * qx + qy * qy);
}
///
@ -767,6 +796,26 @@ T abs(T)(Complex!T z) @safe pure nothrow @nogc
assert(abs(complex(1.0L, -2.0L)) == core.math.sqrt(5.0L));
}
@safe pure nothrow unittest
{
{
auto x = Complex!float(-5.016556e-20, 0);
assert(x.abs == 5.016556e-20f);
auto x1 = Complex!float(-5.016556e-20f, 0);
assert(x1.abs == 5.016556e-20f);
auto x2 = Complex!float(5.016556e-20f, 0);
assert(x2.abs == 5.016556e-20f);
}
{
import std.math.traits : isNaN, isInfinity;
assert(Complex!double(double.nan, 0).abs.isNaN);
assert(Complex!double(double.nan, double.nan).abs.isNaN);
assert(Complex!double(double.infinity, 0).abs.isInfinity);
assert(Complex!double(0, double.infinity).abs.isInfinity);
assert(Complex!double(0, 0).abs == 0);
}
}
@safe pure nothrow @nogc unittest
{
static import core.math;
@ -788,6 +837,7 @@ T abs(T)(Complex!T z) @safe pure nothrow @nogc
}}
}
/++
Params:
z = A complex number.
@ -812,6 +862,7 @@ T sqAbs(T)(Complex!T z) @safe pure nothrow @nogc
assert(isClose(sqAbs(complex(1.0f,-1.0f)), 2.0f));
}
/// ditto
T sqAbs(T)(const T x) @safe pure nothrow @nogc
if (isFloatingPoint!T)