# Question:how to map an operation on columns (or rows) of a matrix

## Question:how to map an operation on columns (or rows) of a matrix

Maple

Maple 16:

```Given Matrix A of size nRow,nCol, and a vector b of size nCol, I wanted to divide each value in column
K by b(K) where k=1..nCol and the result will be a matrix B also of size nRow,nCol ofcourse.

For example, I want to do A[..,1]/b[1],  A[..,2]/b[2], etc.. for each column of A

The way I do it now is by using seq(), then convert the result to matrix, like this:

```
```
nCol := LinearAlgebra:-ColumnDimension(A):
B    := convert([seq(A[..,i]/b[i],i=1..nCol)],Matrix);

```
```And it works.  But was wondering if there is a better way to do this. I tried to use apply map but did
not know how to```
```Here is below the complete Maple 16 code I have:

------------------------
A := LinearAlgebra:-RandomMatrix(3,4);
b := MTM:-sum(A,1);
nCol := LinearAlgebra:-ColumnDimension(A):
B := convert([seq(A[..,i]/b[i],i=1..nCol)],Matrix);
MTM:-sum(B,1);  #verify the sum is 1

```
﻿