public static float fastangle(float4 from, float4 to) => (math.dot(from, to) / (from.lengthsq() * to.lengthsq()).fastsqrt()).npsaturate().acos();
/// <inheritdoc cref="angle(float3,float3)"/>
public static float angle(float4 from, float4 to)
{
var num = (from.lengthsq() * to.lengthsq()).sqrt();
return(num < 1.00000000362749E-15f ? 0 : (math.dot(from, to) / num).npsaturate().acos()); // * 57.29578f;
}