# How to graph a cumulative subtraction on Wolfram Alpha

I'd like to graph a timing algorithm that I'd been using (that did essentially the opposite of what I wanted). I apologize if I'm not using the correct name to refer to it.

Essentially it was timer = 100, timer = timer - level, where level increases from 0 to 50 etc.

For example; 100-1 = 99, 99-2 = 97, 97-3 = 94, 94-4 = 90, etc...

To give you some examples of the kind of graph I'd like, input the following two which were used to create the correct algorithm (a sort of exponential decay);

y=100\cdot e^{-0.05x} with x from 0 to 50

y=100*0.95^{x} with x from 0 to 50

(I'm writing a little article about the improved timer, and I'd like to include graphs of the old and new algorithms for comparison.) Thank you in advance. :)

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A friend figured it out finally: wolframalpha.com/input/… –  Justin Stressman Dec 9 '11 at 7:47

FIRST I changed it to going from $500$

Secondly, it actually gives an alternate interpretation for the summation, and once THAT is punched in, guess what ;)

y=500-(0.5x(x+1)) from x=0 to x=31

Wolframalpha input

It's too bad that I couldn't get the $x\gt0$ plotting to work with sigma notation, but this works :)

y=100-( sum j, j=1 to x)

Wolframalpha input

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