Calculates a 'Fourier elliptical shape' given Fourier coefficients

## Usage

```
efourier_shape(
an = NULL,
bn = NULL,
cn = NULL,
dn = NULL,
n = 1,
nharm = NULL,
npoints = 150,
alpha = 4,
plot = TRUE
)
```

## Arguments

- an
The \(a_n\) Fourier coefficients on which to calculate a shape.

- bn
The \(b_n\) Fourier coefficients on which to calculate a shape.

- cn
The \(c_n\) Fourier coefficients on which to calculate a shape.

- dn
The \(d_n\) Fourier coefficients on which to calculate a shape.

- n
The number of shapes to generate. Defaults to 1. If more than one shape is used, a list of coordinates is returned.

- nharm
The number of harmonics to use. It must be less than or equal to the length of

`*_n`

coefficients.- npoints
The number of points to calculate.

- alpha
The power coefficient associated with the (usually decreasing) amplitude of the Fourier coefficients.

- plot
Logical indicating Whether to plot the shape. Defaults to ´TRUE`

## Details

`efourier_shape`

can be used by specifying `nharm`

and
`alpha`

. The coefficients are then sampled in an uniform distribution
\((-\pi ; \pi)\) and this amplitude is then divided by \(harmonicrank ^
alpha\). If `alpha`

is lower than 1, consecutive coefficients will thus
increase. See Claude (2008) pp.223 for the maths behind inverse ellipitical
Fourier

Adapted from Claude (2008). pp. 223.