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Canonical correlation

`[A,B] = canoncorr(X,Y)`

[A,B,r] = canoncorr(X,Y)

[A,B,r,U,V] = canoncorr(X,Y)

[A,B,r,U,V,stats] = canoncorr(X,Y)

`[A,B] = canoncorr(X,Y)`

computes
the sample canonical coefficients for the `n`

-by-`d1`

and `n`

-by-`d2`

data
matrices `X`

and `Y`

. `X`

and `Y`

must
have the same number of observations (rows) but can have different
numbers of variables (columns). `A`

and `B`

are `d1`

-by-`d`

and `d2`

-by-`d`

matrices,
where `d = min(rank(X),rank(Y))`

. The `j`

th
columns of `A`

and `B`

contain the
canonical coefficients, i.e., the linear combination of variables
making up the `j`

th canonical variable for `X`

and `Y`

,
respectively. Columns of `A`

and `B`

are
scaled to make the covariance matrices of the canonical variables
the identity matrix (see `U`

and `V`

below).
If `X`

or `Y`

is less than full
rank, `canoncorr`

gives a warning and returns zeros
in the rows of `A`

or `B`

corresponding
to dependent columns of `X`

or `Y`

.

`[A,B,r] = canoncorr(X,Y)`

also
returns a 1-by-`d`

vector containing the sample canonical
correlations. The `j`

th element of `r`

is
the correlation between the *j*th columns of `U`

and `V`

(see
below).

`[A,B,r,U,V] = canoncorr(X,Y)`

also
returns the canonical variables, scores. `U`

and `V`

are `n`

-by-`d`

matrices
computed as

U = (X-repmat(mean(X),N,1))*A V = (Y-repmat(mean(Y),N,1))*B

`[A,B,r,U,V,stats] = canoncorr(X,Y) `

also returns a structure `stats`

containing information
relating to the sequence of `d`

null hypotheses $${H}_{0}^{(k)}$$, that the (`k+1`

)st
through `d`

th correlations are all zero, for ```
k
= 0:(d-1)
```

. `stats`

contains seven fields,
each a `1`

-by-`d`

vector with elements
corresponding to the values of `k`

, as described
in the following table:

Field | Description |
---|---|

`Wilks` | Wilks' lambda (likelihood ratio) statistic |

`df1` | Degrees of freedom for the chi-squared statistic, and
the numerator degrees of freedom for the |

`df2` | Denominator degrees of freedom for the |

`F` | Rao's approximate |

`pF` | Right-tail significance level for |

`chisq` | Bartlett's approximate chi-squared statistic for $${H}_{0}^{(k)}$$ with Lawley's modification |

`pChisq` | Right-tail significance level for |

`stats`

has two other fields (`dfe`

and `p`

)
which are equal to `df1`

and `pChisq`

,
respectively, and exist for historical reasons.

[1] Krzanowski, W. J. *Principles
of Multivariate Analysis: A User's Perspective*. New York:
Oxford University Press, 1988.

[2] Seber, G. A. F. *Multivariate
Observations*. Hoboken, NJ: John Wiley & Sons, Inc.,
1984.

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