# ortho: Test a matrix of contrast coefficients for pairwise... In asuR: Advanced statistics using R

## Description

This function tests all pairwise contrast coefficients for orthogonality. The function tells the user which pair of contrasts are not orthogonal.

## Usage

 `1` ```ortho(contr, round = 10) ```

## Arguments

 `contr` A matirx, wiht k-1 rows (one for each contrast) and k columns one for each level of a factor. `round` To test if the sum of the products of the coefficients is zero the sum is rounded using this value as digits argument for round.

## Details

For all pairs of contrasts coefficients the sum of the products of the coefficients is calculated and compared if it is zero or not.

a logical

## Note

There are more elegant solutions to this problem but this one tells the user which pairs of contrasts are not orthogonal.

## References

none

`mancontr`
 ```1 2 3 4 5``` ```trt.contr <- rbind("control-sugar"=c(1, -1/4, -1/4, -1/4, -1/4), "pure-mixed"=c(0, 1/3, 1/3, -1, 1/3), "monosaccharides-disaccharides"=c(0,1/2,1/2,0,-1), "gluc-fruc"=c(0,1,-1,0,0)) ortho(trt.contr) ```