Matlab-Matrix - Multippcation

Consider two matrices A and B. If A is an m x n matrix and B is an n x p matrix, they could be multipped together to produce an m x n matrix C. Matrix multippcation is possible only if the number of columns n in A is equal to the number of rows n in B.

In matrix multippcation, the elements of the rows in the first matrix are multipped with the corresponding columns in the second matrix.

Each element in the (i, j)thposition, in the resulting matrix C, is the summation of the products of elements in ith row of the first matrix with the corresponding element in the jth column of the second matrix.

Matrix multippcation in MATLAB is performed by using the * operator.

Example

Consider following example in MATLAB

a = [ 1 2 3; 2 3 4; 1 2 5];
b = [ 2 1 3 ; 5 0 -2; 2 3 -1];
prod = a * b

Output

The execution in MATLAB will display the following result −

>> a = [ 1 2 3; 2 3 4; 1 2 5];
b = [ 2 1 3 ; 5 0 -2; 2 3 -1];
prod = a * b


prod =

    18  10  -4
    27  14  -4
    22  16  -6
 
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The mtimes function

You can also make use of the function mtimes to multiply two given matrices. It is a builtin function available in MATLAB.

Example

Consider following example −

a = [ 1 2 3; 2 3 4; 1 2 5];
b = [ 2 1 3 ; 5 0 -2; 2 3 -1];
test= mtimes(a,b)

Output

On execution in MATLAB the output is as follows −

>> a = [ 1 2 3; 2 3 4; 1 2 5];
b = [ 2 1 3 ; 5 0 -2; 2 3 -1];
test= mtimes(a,b)


test =

    18  10  -4
    27  14  -4
    22  16  -6
      
>>