# Ncchi2cdf

Ncchi2cdf-func

## Definition:

computes the probability associated with the lower tail of the non-central distribution.

The lower tail probability of the non-central distribution with degrees of freedom and non-centrality parameter , is defined by:

.

where is a central with degrees of freedom.

## Parameters:

- x (input,double)
- The deviation from the non-central distribution with degrees of freedom and non-centrality parameter . .
- f (input,double)
- The degrees of freedom, , of the non-central distribution. .
- lambda (input,double)
- The non-centrality parameter, , of the non-central distribution. lambda > 0 if ; lambda if .
- prob (output,double)
- The probability.