Difference between the usage of sum functions

Hey, can someone explain, why the results are different? And which way is the right one? Thanks.

X=A+B+C-D;
Sum1=sum(X)
Sum2=sum(A)+sum(B)+sum(C)-sum(D)

Answer 1

[madhan ravi]

SUM1 is the right one.

It calculates your resultant matrix’s sum

But the latter calculates the sum o each matrices and does the arithmetic operations but then also it depends on your wish.

[Benedikt Wessel]

Thanks!

[madhan ravi]

you’re welcome you can also vote for the answer