arrays have incompatible sizes for this operation. error in gradientdescentmulti (line 19) h = x.* theta; related documentation in matlab

The error "arrays have incompatible sizes for this operation" in the function gradientdescentmulti (line 19) occurs when the sizes of the arrays involved in the operation are not compatible.

In the specific line of code you mentioned, h = x .* theta;, it seems like you are trying to perform an element-wise multiplication between the arrays x and theta.

To avoid the error, make sure that the sizes of x and theta are compatible for element-wise multiplication. In MATLAB, for element-wise multiplication, the arrays should either have the same size or one of them should be a scalar.

Here are some possible solutions depending on your specific case:

1. If x and theta have the same size, you can directly perform the element-wise multiplication as h = x .* theta;.

2. If theta is a scalar, you can multiply it element-wise with each element of x using the .* operator as follows:

   main.m
   h = x .* theta;
   16 chars
   2 lines

3. If x is a scalar, you can multiply it element-wise with each element of theta using the .* operator as follows:

   main.m
   h = theta .* x;
   16 chars
   2 lines

Make sure to check the sizes of x and theta and choose the appropriate solution based on your specific case.

For more information, you can refer to the MATLAB documentation on element-wise operations:

• Element-wise Array Operations
• Array vs. Matrix Operations

Remember to also check the other parts of your code to ensure there are no other instances of incompatible array sizes that could lead to this error.