Statistics Toolbox |

Normal cumulative distribution function (cdf)

**Syntax**

**Description**

```
normcdf(X,MU,SIGMA)
```

computes the normal cdf at each of the values in `X`

using the corresponding parameters in MU and SIGMA. Vector or matrix inputs for X, MU, and SIGMA must all have the same size. A scalar input is expanded to a constant matrix with the same dimensions as the other inputs. The parameters in SIGMA must be positive.

The result, *p*, is the probability that a single observation from a normal distribution with parameters µ and will fall in the interval (- *x*].

The *standard normal* distribution has µ= 0 and = 1.

**Examples**

What is the probability that an observation from a standard normal distribution will fall on the interval [-1 1]?

More generally, about 68% of the observations from a normal distribution fall within one standard deviation, , of the mean, *µ*.

**See Also**

`cdf`

, `normfit`

, `norminv`

, `normpdf`

, `normplot`

, `normrnd`

, `normspec`

, `normstat`

nlpredci | normfit |