## NAME

topolar -- Convert from real and imaginary parts to amplitude and phase.

## USAGE

`topolar input ampl phase`

## DESCRIPTION

This task takes a pair of images,
real and imaginary parts of a Fourier transform,
and converts them to the amplitude and phase.
As with other tasks in the `fourier` package,
the names of the real and imaginary parts are produced by appending
"r" and "i" respectively to the name specified by the parameter `input`.
For each pixel, the amplitude is the square root of the sum of the
squares of the real and imaginary parts,
and the phase is the arctangent: ATAN2 (imaginary, real).
The phase is in radians within the interval (-pi,+pi).

## PARAMETERS

- input = "" [file name]
- Name of the input image.
The letters "r" and "i" will be appended to the name to form the names of the images for real and imaginary parts respectively. It is an error if either the real or imaginary part does not exist.

- ampl = "" [file name]
- Name of the output image for the amplitude.

- phase = "" [file name]
- Name of the output image for the phase.

## EXAMPLES

1. Converts real part `x00w6601rr.d0h` and imaginary part
`x00w6601ri.d0h` to amplitude `a.hhh` and phase `ph.hhh`.

fo> topolar x00w6601r.d0h a.hhh ph.hhh

## BUGS

## SEE ALSO

Type "help fourier option=sys" for a higher-level description of
the `fourier` package.