Why do I receive the error message "Arrays have incompatible sizes for this operation"?

Why does this error occur?

Arrays have incompatible sizes for this operation. 

Error in fitting_method_iefa (line 238) 
Different2 = sum((y-Convolution).^2);

[Dyuman Joshi]

The reason is stated in the error - "Arrays have incompatible sizes for this operation."

For e.g., you can not subtract a 2x3 array from a 3x2 array. Thus, for substraction these arrays have incompatible size.

Check the size of the arrays "y" and "Convolution".

[Walter Roberson]

The story sometimes gets told that originally Loren phrased the error message as "Didn't Think Twice. Wasn't All Right." but that George didn't like The Greatful Dead and made her change the message.

[Thiripura Sundari]

Arrays have incompatible sizes for this operation.

Error in guna1 (line 32)

RHS = (theta(2:end-1,j)/dt) + Ec*((diff(u(:,j))./dy).^2) - Q*0.5*(theta(3:end,j)-theta(2:end-1,j))

give answer

[Dyuman Joshi]

@Thiripura Sundari, it would be much better if you ask a new question of your own and provide relevant information to solve the issue.

Also check this (self-explanatory) thread - TUTORIAL: how to ask a question (on Answers) and get a fast answer

Answer 1

[Sourabh]

The following error in MATLAB occurs when you try to perform operations (such as subtraction) on two arrays that have different sizes or dimensions that are not compatible with each other.

Arrays have incompatible sizes for this operation

You can understand array size compatibility from the following link:

https://www.mathworks.com/help/matlab/matlab_prog/compatible-array-sizes-for-basic-operations.html

Try using the "size" function to find out the dimensions of an array.

[SergeyLA]

Sourabh, you provided answer which gives no solution to this error!

Please check following code, where 'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141' is the hex number stronger LESS than 2^256, but MATLAB ends with error despite claimed realmax=(2-2^(-52))*2^1023.

X = hex2num('fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141')

Arrays have incompatible sizes for this operation.

Error in hex2num>hex2decImpl (line 51)
num = flip((16*num(:, 1:2:end) + num(:, 2:2:end)).');

Error in hex2num (line 7)
x = hex2decImpl(s);

[Steven Lord]

This is not a bug in MATLAB, as explained in the comments and answers on your other post here.

[Walter Roberson]

@SergeyLA

Thank you for reporting this bug in hex2num. The intended internal behaviour was to remove all columns past the 16th, but instead the code was removing only the last column when there were more than 16.