How to subtract from a vector, have it return a value of zero if the answer is less than zero, and then tell me how much was subtracted?

I essentially need to write a function like this:

x=[1, 2 3]
y= 2
x(1) - y
if x(1)<0
    totalsubtracted = y +x(1)
x(1)=0
else
    totalsubtracted = x(1)-y
end

But without conditionals. How do I do this?

Answer 1

[madhan ravi]

    totalsubtracted = (x(1) < 0) * (y + x(1)) + (x(1) > 0) * (- y + x(1)) % ?

[Brett Baxter]

That works only if the result is negative. I would need it to also work if the result is positive.

Like if x(1)>2 and y = 2

this would mean that x(1) = x(1)-y would give an output that was greater than or equal to 1, which is positive. When I run that script, it doesn't give me the total subtracted as 2 like it should

[madhan ravi]

x = [1, 2, 3]
y = 2
% Desired result?

[Brett Baxter]

Let me be a little more specific

Imagine I had a vector of some numbers like

x =[55 65 70]

and I wanted to subtract some input value from the first number in this vector, like so

y = 65
x(1) = x(1) - y

This would produce the following result under normal circumstances

x = -10 65 70

Now what I need matlab to do: if x(1) is a negative number after subtraction, then x(1) needs to be set to 0, like so

x = 0 65 70

Then, I need matlab to tell me how much was subtracted from x(1). If the number returned in x(1) is negative after subtraction, I need it to tell me how much was subtracted from x(1) barring any numbers less than 0. So, in this case, I want it to tell me

totalsubtracted = 55

But, if x(1) is not negative, I need it to tell me how much it subtracted. Like the following

x = [70 65 70]
y = 65
x(1) = x(1) - y
x = 5 65 70
totalsubtracted = 65

does this make sense? I need to do this WITHOUT using any conditionals

[madhan ravi]

“ WITHOUT using any conditionals”

Isn’t that your homework?

 x(1) = x(1) * (x(1) > 0)
 totalsubtracted = y

[Brett Baxter]

It isn't all of my homework, it's only a specific part that I need for a later part. I've run into this problem because I don't know how else to get this without using conditionals. The numbers I have in my question are only as an example of what I'm trying to accomplish.

[Brett Baxter]

Yes, that works, but if the resulting value is negative, y does not equal total subtracted. I know it sounds silly but if the resulting value is negative, then the total subtracted needs to come back as the value subtracted from x(1) up until it became less than 0

like I said earlier

x(1) = 1
y = 2
x(1) = x(1) - y
%this would then return a vector where
x(1) = -1

Yes, the total subtracted would be the value of y, but I need matlab to tell me how much was subtracted BEFORE the value went below 0

so in this case

%I'm looking for this answer
totalsubtracted = 1
%NOT this answer
totalsubtracted = 2

I need this to work for both cases, where x(1) > 0 and x(1) < 0 without any conditionals

[madhan ravi]

Ok ,so wait for the response. Don’t ask the same question a billion times before responding here.

[Brett Baxter]

I was responding to the edited comment you made