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I have problem to draw in Mathematica a plot like this:

Plot[{Sum[a^10*(-1)^(x-a), {a, 1, x}]}, {x, 1, 10}]

The problem is that on the plot there is no graph. As it can be calculated, there should be some values plotted. When I try to draw this equation in Mathematica as

plot (sum(a^10*(-1)^(x-a),a=1 to x)), x = 1 to 10 

everything works fine, so I think I did something wrong with the first command in Mathematica, but I can't find the mistake.

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marked as duplicate by rm -rf Dec 5 '13 at 8:46

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

    
The same question on StackExchange: "Plot with sum commend." –  Alexey Popkov Dec 5 '13 at 6:45
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1 Answer 1

up vote 4 down vote accepted

Plot has attributes, HoldAll, so the Sum isn't evaluated,

try this:

Plot[Evaluate[Sum[a^10*(-1)^(x - a), {a, 1, x}]], {x, 1, 10}]

Where the sum evaluates to:

Mathematica graphics

before plotting:

enter image description here

related questions/answers:

Difference in Plot when using Evaluate vs when not using Evaluate

How and when to use Evaluate?

Behavior of expression evaluation in Plot

I prefer a different domain:

Plot[Evaluate[Sum[a^10*(-1)^(x - a), {a, 1, x}]], {x, -3, 2}]

Mathematica graphics

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Yeah, that's it –  belisarius Dec 5 '13 at 3:34
    
@s0rce I have one more problem when i Want to draw this: Plot[Evaluate[Sum[Binomial[x, l]*l^10*(-1)^(x - l), {l, 0, x}]], {x, 1,2}], no graph is plotted, and I can't notice way, because if I will calucate this, there should be some points –  Ziva Dec 6 '13 at 0:35
    
@Ziva the result of your sum seems to be only defined for integers. –  s0rce Dec 6 '13 at 4:35
    
@sOrce, Yes, you are right! I forgot to restrict x to integers. –  Ziva Dec 6 '13 at 10:25
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