Add value x to negaive numbers and subtract value x from positiv numbers in same double

Hi there,

lets say i the double [5 4 3 2 1 -1 -2 -3 -4 -5] and the value x=0.5.

I would like to subtract x from all positiv numbers of the double and add x to all negative numbers. How to go about this ?

Thanks for your time and help

Ben !

Answer 1

[John D'Errico]

Trivial. Though you do not say what happens to zero.

V = [5 4 3 2 1 -1 -2 -3 -4 -5];
x = 0.5;

V - x*sign(V)

ans = 1×10

4.5000 3.5000 2.5000 1.5000 0.5000 -0.5000 -1.5000 -2.5000 -3.5000 -4.5000

As I said, It is very important in computing to consider the special cases, as if you don't do that then you will find bugs arise.

sign(0)

ans = 0

So what happens if V has an exactly zero element? Since sign(0) is zero, it leaves the zero alone.