[R] Help with Functions

[Lord Tyranus]

Hello wizards, I need to convert the following functions (prestd,
poststd, prepca)   of matlab to R. Does Somebody knows how to do it. A
description of the functions is:

prestd preprocesses the network training set by normalizing the inputs
and targets so that they have means of zero and standard deviations of
1.

poststd postprocesses the network training set which was preprocessed
by prestd. It converts the data back into unnormalized units.

prepca preprocesses the network input training set by applying a
principal component analysis. This analysis transforms the input data
so that the elements of the input vector set will be uncorrelated. In
addition, the size of the input vectors may be reduced by retaining
only those components which contribute more than a specified fraction
(min_frac) of the total variation in the data set.

Thanks in advance.