Can't get function to accept array params or return arrays

Consider this function to calculate the slope of a line:

function [m] = f_GetSlope(x1, y1, x2, y2)
m = (y1 - y2)/(x1 - x2);

It works with scalar inputs. But I want to call it like so:

aX1 = [1, 23];
aY1 = [1, 12];
aX2 = [2, 8];
aY2 = [2, 0];
m1 = f_GetSlope(aX1, aY1, aX2, aY2)

Ideally it would return:

m1 = 1   0.800

In actuality:

m1 = 0.8009

Just one return value, and not correct for either set of inputs.

What am I doing wrong?

Answer 1

[Cedric]

You want to use an element-by-element operator for the division:

 m = (y1 - y2)./(x1 - x2);

[Emma]

Interesting.

[Cedric]

Yes, some operators have a mathematical definition when applied on matrices that is different from the element-wise type of operations.

http://www.mathworks.com/help/matlab/matlab_prog/operators.html

The most typical case is probably the matrix multiplication * (performed according the the mathematical def. of matrix multiplication), which is completely different from the element-wise multiplication .* (multiplication element-by-corresponding-element between two arrays with same size).