well i have to build an expert system using four variables, in each of these variables there are six columns and 24000 rows and i need to use PCA to reduce the data. the following code only allows me to reduce six rows of one variable at a time, [pn,meanp,stdp] = prestd(p); [ptrans,transMat] = prepca(pn,0.02); do you have any suggestions in reducing the whole amount of data? thanks