How can I fix the error when multiple two matrices?

I have two (100*1) matrices. When I multiple them, an error occured "??? Error using ==> mtimes Inner matrix dimensions must agree. Please help me to fix it

Answer 1

[James Tursa]

Did you mean element-wise multiplication? If so, use the .* operator. E.g.,

a = your 100 x 1 vector
b = your 100 x 1 vector
result = a .* b;

Answer 2

[Steven Lord]

How do you want to multiply them? Element-by-element, to generate a vector the same size as x and y where each element is the product of the corresponding elements in x and y?

 x = (1:10).';
 y = (1:10).';
 z1 = x.*y; % NOTE the period
 isequal(z1(4), x(4)*y(4)) % for scalar multiplication, the * and .* operators are the same

Do you want to generate a 1-by-1, the dot product of the two vectors?

 z2 = dot(x, y);
 z3 = x.'*y;
 isequal(z2, sum(x.*y))
 isequal(z2, z3)

Do you want to generate a 10-by-10 matrix, the multiplication table for x and y?

 z4 = x*y.';
 isequal(z4(7, 8), x(7)*y(8))
 multiplicationTable = [NaN, y.'; x, z4]