Matrix dimensions must agree when doing an elementwise operation

a = 0:1:100;
b = 0:1:100;
c = 0:1:360;
r = 3.3*10^-2;
d = (a+b).*cos(c).*r./2;

Hello, I would like to compute the program with the following code above

When I run the program, I get this error like this.

could anyone explain me what's wrong?

Answer 1

[John D'Errico]

How many elements are there in the vector a? (101)

How many elements are there in the vector b? (101)

How many elements are there in the vector c? (361)

Addition of a+b works, because there are the same number of elements in the two vectors.

But then elementwise multiplication would have MATLAB multiply EVERY element of (a+b) with the corresponding element of cos( c). How will that be expected to work? (Poorly.)

MATLAB has no problem mutiplying by r/2, because r is a scalar.

If you want to fix that, then a,b,c all need to have the same number of elements.

[Michael Andersen]

thank you for the answer,

actually i want to find "d" value from a,b, and c data every row like this picture

do you know how to solve? thanks

Answer 2

[Torsten]

Yes, a,b and c must have the same number of elements for that an elementwise multiplication makes sense.

Maybe you mean

d = (a+b).'*cosd(c)*r/2;

?

[Michael Andersen]

thank you for the answer,

actually i want to find "d" value from a,b, and c data every row like this picture

do you know how to solve? thanks

[Torsten]

a = 0:1:100;
b = 0:1:100;
c = 0:1:360;
r = 3.3*10^-2;
[A,B,C] = ndgrid(a,b,c);
D = (A+B).*cosd(C)*r/2