Create vectors by taking different number of columns from matrix

Hello to everyone,

so i have a matrix (dimension1*298) and a vector with values count=(51,25,78,48,48,48)'. I want to create 6 new vectors from this matrix, each of which will has

length1= dimension1*value(count(1))=dimension1*51, (take the first 51 columns from the matrix for the first vector)

length2=dimension1*value(count(2))=dimension1*25 (take the next 25 columns from the matrix for the first vector)

and so on.

So practically i create from my big matrix new vectors which will comprise from its columns. But the problems is that those vectors will have different lengths.

Any ideas?