Plot derivative of integral with changing limits

Asked Apr 28 '13 at 18:52

Active Apr 28 '13 at 18:52

Viewed 51 times

My code is: Plot[D[Integrate[E^(t*(-x^2)),{x,t+2,t^2}],t],{t,-2,3}].

The errors/warnings are:

General::ivar: "-1.9999 is not a valid variable."

General::ivar: "-1.89786 is not a valid variable."

General::ivar: "-1.79582 is not a valid variable."

General::stop: "Further output of \!$\* StyleBox[ RowBox[{\"General\", \"::\", \"ivar\"}], \"MessageName\"]$ will be suppressed during this calculation. "

The graph turns out empty in the end.

What did I do wrong this time?

asked Apr 28 '13 at 18:52

user76568

Use Evaluated->True in Plot. – Spawn1701D Apr 28 '13 at 18:54
That worked... Thanks. What does it try to do if I DON'T add this property? – user76568 Apr 28 '13 at 18:56
If you check Plot's Attributes you will see that has the HoldAll attribute, hence the expression will remain unevaluated. – Spawn1701D Apr 28 '13 at 18:56
Yes, or Plot[Evaluate@D[Integrate[E^(t*(-x^2)),{x,t+2,t^2}],t],{t,-2,3}]. I'm sure this is a duplicate question, but too lazy to look now:) – Ajasja Apr 28 '13 at 18:56
@Spawn1701D , If I intend to plot something, in what circumstances will I want the expression to remain not evaluated...? – user76568 Apr 28 '13 at 18:58
Same question for @Ajasja :) – user76568 Apr 28 '13 at 19:01
When it's just a formula ($t^2$) or you give a function ($f(x)$) to name a few. – Spawn1701D Apr 28 '13 at 19:06
1

It's a duplicate of this question, which a duplicate of another question. – Michael E2 Apr 28 '13 at 21:23

Plot derivative of integral with changing limits

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