# diffop keywords

Differential operator parameters

## diffop.accuracy

Determine the accuracy of the finite difference stencil; even integer
only; referenced only if diffop.method = \'fd\'; for smooth function the
error in the derivatives scales as O(h\^alpha) where alpha =
diffop.method.

**type**: `scalar`

**default**: `16`

**example**: `diffop.accuracy = 12`

## diffop.method

Determine the differentiation method; \'fd\' uses finite difference
coefficients to evaluate derivatives; \'ft\' uses Fourier coefficients
to evaluate derivatives; \'fft\' uses the fast Fourier transform
algorithm to evaluate derivatives

**type**: `string`

**default**: `'fd'`

**allowed**: `'fd', 'ft', 'fft'`

**example**: `diffop.method = 'fft'`
