How can I write looping data matrix into same excel file?

I have a looping data matrix in matlab, and I want to write it into same excel file. If I use the xlswrite('name.xls', M) it'll make a 'name.xls' excel, contained one matrix (value of the last looping). How can I write all my looping matrix (lets say it has 10 matrix with 13 columns) in one file excel and that excel file will contain all my matrix with 13 columns (so there'll be 10 rows with 13 columns). Please help, Thanks. -Machmum