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# cdft_t

Calculates the t-value given the one-sided probability and the degrees of freedom.

## Prototype

```	function cdft_t (
p   : numeric,
df  : numeric
)

return_val  :  numeric
```

## Arguments

p

A scalar or array containing probabilities ( 0 <= p < 1 ).

df

A scalar or array of the same size as p containing the number of degrees of freedom.

## Return value

A array of the same size as p. Double if any of the input arguments are double, float otherwise.

## Description

Using the cumulative distribution function for the T distribution, calculate the t-values associated with one or more probabilities and degrees of freedom. Technically, this is the upper limit of integration of the t-density distribution.

The source code is from source routine "CDFT" from DCDFLIB (Double precision Cumulative Distribution Function LIBrary).

## Examples

Example 1

```     df = 16

p  = 0.025
T = cdft_t(p, df)    ; T = -2.12

p  = 0.975
T = cdft_t(p, df)    ; T =  2.12
```