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Standardized *z*-scores

`Z = zscore(X)`

`Z = zscore(X,flag)`

`Z = zscore(X,flag,dim)`

```
[Z,mu,sigma]
= zscore(___)
```

returns
the `Z`

= zscore(`X`

)*z*-score for
each element of `X`

such that columns of `X`

are
centered to have mean 0 and scaled to have standard deviation 1. `Z`

is
the same size as `X`

.

If

`X`

is a vector, then`Z`

is a vector of*z*-scores.If

`X`

is a matrix, then`Z`

is a matrix of the same size as`X`

, and each column of`Z`

has mean 0 and standard deviation 1.For multidimensional arrays,

*z*-scores in`Z`

are computed along the first nonsingleton dimension of`X`

.

scales `Z`

= zscore(`X`

,`flag`

)`X`

using
the standard deviation indicated by `flag`

.

If

`flag`

is 0 (default), then`zscore`

scales`X`

using the sample standard deviation, with*n*- 1 in the denominator of the standard deviation formula.`zscore(X,0)`

is the same as`zscore(X)`

.If

`flag`

is 1, then`zscore`

scales`X`

using the population standard deviation, with*n*in the denominator of standard deviation formula.

`zscore`

returns `NaN`

s for
any sample containing `NaN`

s.

`zscore`

returns `0`

s for
any sample that is constant (all values are the same). For example,
if `X`

is a vector of the same numeric value, then `Z`

is
a vector of `0`

s. If `X`

is a matrix
with a column of consisting of the same value, then that column of `Z`

consists
of `0`

s.

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