## Prefactor

`Prefactor` is an option for `OneLoop` and `OneLoopSum`. If set as option of `OneLoop`, the amplitude is multiplied by `Prefactor` before calculation; if specified as option of `OneLoopSum`, after calculation in the final result as a global factor.

### See also

[Overview](Extra/FeynCalc.md), [OneLoop](OneLoop.md), [OneLoopSum](OneLoopSum.md).

### Examples