The default math functions in .Net are realized with static methods from the Math class. However, many operations work on doubles by default (like Math.Sin) and there is often no float overload. This causes many floating-point operations to be performed on 64-bit floats, even when this precision is not required. .Net Core and .Net Standard compatible frameworks ship the MathF class to overcome this limitation. ILGPU offers the IntrinsicMath class that supports basic math operations which are supported on all target platforms. The algorithms library offers the XMath class that has support for all common 32-bit float and 64-bit float math operations. Using the 32-bit overloads ensure that the operations are performed on 32-bit floats on the GPU hardware.

Fast Math

Fast-math can be enabled using the Math(MathMode.Fast) method of Context.Builder and enables the use of fast (and unprecise) math functions. Unlike previous versions, the fast-math mode applies to all math instructions. Even to default math operations like x / y.

Context context = Context.Create(builder => builder.Math(MathMode.Fast));

Forced 32-bit Math

Your kernels might rely on third-party functions that are not under your control. These functions typically depend on the default .Net Math class, and thus, work on 64-bit floating-point operations. You can force the use of 32-bit floating-point operations in all cases using the Math(MathMode.Fast32BitOnly) method of Context.Builder.

Context context = Context.Create(builder => builder.Math(MathMode.Fast32BitOnly));

Caution: All doubles will be considered as floats to circumvent issues with third-party code. However, this also affects the address computations of array-view elements. Avoid the use of this flag unless you know exactly what you are doing.