I am getting an error "Variable a must be of data type char. It is currently of type double. Check where the variable is assigned a value."

Question:

Using matrix multiplication, multiply A1 by A1, set to a

Using matrix multiplication, multiply v1 by A1, set to c

Input: A1 = [-2:1; 1:-1:-2; -2:2:4]

v1 = linspace(-2,4,4) 
a = A1 .* A1 
c = v1 .* A1 

output:

Variable a must be of data type char. It is currently of type double. Check where the variable is assigned a value.

Answer 1

[Pratik]

Hi Chloe,

In my understanding, you want to perform matrix multiplication between A1 & A1 , v1 & A1. The operator to perform matrix multiplication is '*' or function ‘mtimes’. Operator '.*' performs element wise multiplication.

I was not able to reproduce the error mentioned in the question with the code provided.

A1 = [-2:1; 1:-1:-2; -2:2:4] 

A1 = 3×4

-2 -1 0 1 1 0 -1 -2 -2 0 2 4

v1 = linspace(-2,4,4) 

v1 = 1×4

-2 0 2 4

a = A1 .* A1 

a = 3×4

4 1 0 1 1 0 1 4 4 0 4 16

c = v1 .* A1

c = 3×4

4 0 0 4 -2 0 -2 -8 4 0 4 16

For matrix multiplication of matrices A and B, the number of columns of A must equal the number of rows of B.

Please refer to the documentation of “mtimes” for more information on matrix multiplication:

www.mathworks.com/help/matlab/ref/mtimes.html

Please refer to the documentation of “times” for more information on element wise multiplication:

www.mathworks.com/help/matlab/ref/times.html

I hope this helps!