# 3.5.3.1.19 Normcdf

## Description

Cmputes the probabilities of the specified tail type tail in a given value x, associated with a normal cumulative distribution.

## Syntax

double prob = normcdf(double x,[int tail])

## Parameters

x

Input, the value of the standard Normal variate $\left[ -\infty ,+\infty \right]$

tail

Input, Optional. The tail probability type using for the normal distribution
• 1 = the 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 returned probability.

## Example

normcdf(9.9,3)=;     // ANS: 4.1627504389865E-23