How to reduce the matrix

Sir,

I have a matrix of size 830x27,want to reduce the size to some ax27 using processpca?how to reduce it?

[Zhang lu]

Hi.

a=rand(830,27);
n=10;
for i = 1:floor(size(a,1)/n)
           eval(['a' num2str(i) ' = a(n*(i-1)+1:n*(i-1)+10,:)'])
end

[Minnu]

Now my matrix size is 10x27 .i want to know how to reduce the dimension of matrix without any loss of features

[Zhang lu]

a=rand(830,27);
n=30;
for i = 1:floor(size(a,1)/n)
           eval(['a' num2str(i) ' = a(n*(i-1)+1:n*i,:)'])
end

if mod(size(a,1),n)~=0
    I=floor(size(a,1)/n)+1;
    eval(['a' num2str(I) ' = a(n*i+1:end,:)'])
end

[Jan]

No, Zhang, do not do this. Using EVAL to hide an index in the name of a varibale is a really bad idea. This reduces the processing speed substantially, impedes debugging and required equivalently obtuse methods to access the variables later. It would be tremendously smarter to use an index as index (!):

a{I} = a(n*i+1:end, :)

See Answers: FAQ how can I create A1, A2, ... in a loop