- use matrix operations when doing linear algebra,
- otherwise use array operations.
What am I doing wrong? Matrix operators
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function surfaceArea = surfaceBalloon(Volume,M)
% Your code goes here %
radius = ((3*Volume)./((2+M)*pi))^1/3;
surfaceArea = pi*radius^2.*(2+sqrt(1+M^2));
end
What is wrong with my code? It says:
Error using ^ (line 51)
Incorrect dimensions for raising a matrix to a power. Check that the
matrix is square and the power is a scalar. To perform elementwise
matrix powers, use '.^'.
Error in surfaceBalloon (line 5)
surfaceArea = pi*radius^2.*(2+sqrt(1+M^2));
I thought you didn't have to use dot operators unless you are multiplying, dividing, or raising two matricies. I am raising the radius variable to 1/3 which is a scalar value. Am i missing something?
2 Comments
Stephen23
on 22 Feb 2020
Edited: Stephen23
on 22 Feb 2020
"Am i missing something?"
"I thought you didn't have to use dot operators unless you are multiplying, dividing, or raising two matricies. I am raising the radius variable to 1/3 which is a scalar value."
I don't think that rule-of-thumb is correct. Instead:
Because, as the documentation makes clear, matrix operations apply the rules of linear algebra.
Preet Talati
on 3 Feb 2021
You need to add a dot operator to all the exponent calculations and your 1/3 needs to be (1/3).
Answers (1)
Star Strider
on 22 Feb 2020
If you want to raaise the elements of a matrix to a power, use element-wise exponentiation with the dot operator: .^ and see: Array vs. Matrix Operations for details.
Matrix exponentiation (and several other operattions) are only defined for square matrices. See the Wikipedia article on the Cayley-Hamilton theorem for that discussion.
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