MATLAB: If B is a matrix,what is the difference between B(1:end) and B(:)
matrix manipulation
If B=[1 2 ; 3 4]
B(1:end) returns [1 3 2 4] as a row vector and B(:) returns it as a column vector.
What is the difference?
Best Answer
Given a matrix B:
B(1:end) uses linear indexing. The size of the output is the same as the size of the index (which in your example is a 1xN vector).
B(:) is a special syntax that always returns a column vector.
Loren Shure's blog explained the first syntax as "C = A(B) produces output the size of B unless both A and B are vectors... When both A and B are vectors, the number of elements in C is the number of elements in B and with orientation of A."
a*x is the "usual" matrix-vector multiplication, a.*x is elementwise multiplication. In your case, every element of row i of a is multiplied by the i'th element of the vector x.
Best Answer