function?[presscumpressrmsecvrmsec]?=?crossval（xyrmcvmlvsplititermcoutosc）;
%CROSSVAL?Cross-validation?for?PCA?PLS?and?PCR
%??This?function?does?cross-validation?for?regression
%??and?principal?components?analysis?models?by?several
%??different?methods?including:
%???leave-one-out???????????????（‘loo‘）
%???venetian?blind??????????????（‘vet‘）?
%???continuous?blocks???????????（‘con‘）?
%???repeated?random?test?sets???（‘rnd‘）?
%
%??The?inputs?are?the?scaled?predictor?variable?matrix?（x）?
%??predicted?variable?（y?not?needed?for?PCA?models）?regression?method
%??or?PCA?（rm）?which?can?be:
%???PLS?via?NIPALS?algorithm?（‘nip‘）???（Old?slow?way?of?doing?PLS）
%???PLS?via?SIMPLS?algorithm?（‘sim‘）???（New?fast?way?of?doing?PLS）
%???PCR??????????????????????（‘pcr‘）
%???MLR??????????????????????（‘mlr‘）
%???PCA??????????????????????（‘pca‘）???
%
%??cross-validation?method?（cvm?as?described?above）?number?of?latent?
%??variables?or?principal?components?to?calculate?（lv）?number?of
%??sections?to?split?the?data?into?（split?needed?for?‘vet‘?‘con‘
%??and?‘rnd‘?cross?validations）?number?of?iterations?（iter?needed
%??for?‘rnd‘）?an?optional?variable?which?suppresses?mean?centering
%??of?the?subsets?when?set?to?0?（mc）?an?optional?variable?which
%??supresses?the?output?when?set?to?0?（out）?and?an?optional?variable
%??which?specifies?the?number?of?orthogonal?signal?correction?components
%??to?use?（osc）?which?can?be?a?three?element?vector?which?specifies
%??number?of?components?iterations?and?tolerance?（osc?=?[nocompitertol]）.?
%
%??The?outputs?are?the?predictive?residual?error
%??sum?of?squares?（press）?for?each?subset?and?the?cumulative
%??PRESS?（cumpress）.?Note?that?for?multivariate?y?the?press
%??output?is?grouped?by?output?variable?i.e.?all?of?the?PRESS?values
%??for?the?first?variable?are?followed?by?all?of?the?PRESS?values
%??for?the?second?variable?etc.?Optional?outputs?are?the?root?mean
%??square?error?of?cross-validation?（rmsecv）?and?root?mean?square
%??error?of?（rmsec）.?
%
%I/O:?[presscumpressrmsecvrmsec]?=?crossval（xyrmcvmlvsplititermcoutosc）;
%?
%??Some?examples?of?how?you?might?call?CROSSVAL?are:
%???[presscumpress]?=?crossval（xy‘mlr‘‘loo‘）;
%???[presscumpress]?=?crossval（xy‘nip‘‘loo‘10）;
%???[presscumpress]?=?crossval（xy‘pcr‘‘vet‘103）;
%???[presscumpress]?=?crossval（xy‘nip‘‘con‘105）;
%???[presscumpress]?=?crossval（xy‘sim‘‘rnd‘10320）;
%
%??To?suppress?mean?centering?in?the?first?two?cases:
%???[presscumpress]?=?crossval（xy‘mlr‘‘loo‘[][][]0）;
%???[presscumpress]?=?crossval（xy‘nip‘‘loo‘10[][]0）;
%
%??To?add?orthogonal?signal?correction?with?2?components:
%???[presscumpress]?=?crossval（xy‘sim‘‘vet‘103[][][]2）;
%???[presscumpress]?=?crossval（xy‘pcr‘‘con‘103[][][]2）;
%?
%??For?use?with?PCA?you?might?call?CROSSVAL?like:
%???[presscumpress]?=?crossval（x[]‘pca‘‘loo‘10）;
%???[presscumpress]?=?crossval（x