If you want to combine numbers and texts in a matrix you have to create a cell matrix, a dataset or a table. However, I am not sure I you really want to do that. The solution to your problem depends on what you want to do with the matrix seriesCompl. If you want to perform calcualtions or plot the data in the matrix, then it would be wise to keep the matrix numerical. Instead of writing a name in the third column you could use numbers: series1 = 1, series2 = 2, series3 = 3, ... If you have other plans, then you have to choose a different data type for your matrix (cell, dataset or table).