Simultanious sin(x) and cos(x) calculation.

[QuantifEye]

I am not sure about arm, but x86 has an instruction to calculate sine and cosine in one step.

see https://mudongliang.github.io/x86/html/file_module_x86_id_115.html

It would be great if function public static double SinCos(double x, out double cos); could be added to the System.Math class that calculates sine, and return cosine as an out parameter.

[PathogenDavid]

Math.SinCos and MathF.SinCos were added in #46551 which I would assume will ship with .NET 6.

[tannergooding]

Correct. Likewise, fsincos itself is not a very efficient instruction and would itself likely be slower than just calling Math.Sin and Math.Cos independently.