# Tcdf

Tcdf-func

## Description

Computes the probabilities of the specified tail type **tail**, associated with a cumulative distribution function of Student's t-distribution with the degree of freedom **df**.

## Syntax

double prob = tcdf(double t, double df[, int tail])

## Parameters

**t**

- Input, the value of the Student's variate.[]

**df**

- Input, the degrees of freedom, , of the Student's t-distribution.()

**tail**

- Input, Optional. The tail probability type using for the Student's t-distribution
- 1 = the for upper tail probability
- 2 = the lower tail probability (Default if not set)
- 3 = the two tail (significance level) probability
- 4 = the two tail (confidence interval) probability

**prob**

- Output, the probability.

## Example

tcdf(38.9036068506926,30, 3)=; // ANS: 3.110454711125E-27