# TopoS: Computation of criterion S of a visualization

## Description

`TopoS`

computes one version of the criterion `stress`

as i.e.
known from `sammon`

for a given visualization.

## Usage

TopoS(EV.dist, Cells.dist)

## Arguments

EV.dist

a symmetric distance matrix consisting of distances in the origin space (`dx`

)

Cells.dist

a symmetric distance matrix consisting of distances in the target space (`dy`

)

## Value

`TopoS`

returns a numeric between zero and one which is the criterion `S`

of the given visualization.

## Details

TopoS first performs a homogeneous linear regression where `dx`

is predicted by `dy`

.
Then the residual sum of squares of this regression is computed and divided by the sum of squared `dx`

.
Finally one minus the square root of the latter result defines `S`

.

## Examples

# NOT RUN {
# Compute S for the MDS visualization of the german business data
data(B3)
plot(cmdscale(dist(B3[, 2:14])), col = rainbow(4)[B3[, 1]], pch = 16)
TopoS(dist(B3[, 2:14]), dist(cmdscale(dist(B3[, 2:14]))))
# }