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I am trying to write down the following expression

Integrate[Exp[-a/2/x]/x/(x + 1), {x, 0, b}, Assumptions -> a > 0 && b > 0]

using mathematical notation. I have tried

Assuming[b > 0 && a > 0, Subscript[\[Integral], 0]^b E^(-(a/(2 x)))/(x (x + 1)) \[DifferentialD]x]

and in picture

screenshot of mathematical notation from Mathematica

However, Mathematica returns Syntax: Incomplete expression; more input is needed.

Could you please give guidance what is wrong here? Thank you.

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2 Answers 2

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There is a syntax error with Subscript

Try

Assuming[b > 0 && a > 0, Integrate[Exp[-a/2/x]/x/(x + 1), {x, 0, b}]]
(*-E^(a/2) ExpIntegralEi[-((a (1 + b))/(2 b))]*)
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  • $\begingroup$ Thanks for the answer! However, that is not my question. The first line works fine. I am trying to rewrite it using nice notation. I think that my first line of code Integrate[Exp[-a/2/x]/x/(x + 1), {x, 0, b}, Assumptions -> a > 0 && b > 0] and the screenshot should be equivalent and the former evaluates fine but the latter does not evaluate. The Subscript line is just a copy-paste of the screenshot from the Mathematica editor; I did not enter that. What is wrong in the screenshot? Do I write the integral incorrectly? $\endgroup$
    – drumath
    May 12 at 8:47
  • $\begingroup$ According to Mathematica's manual on Integrate, Subscript should be used to enter $x_{min}$, the lower boundary of the integral, when using "nice notation" (my terminology). $\endgroup$
    – drumath
    May 12 at 8:49
  • $\begingroup$ @drumath Might be! I tried to evaluate your code line(cut&paste) and Mathematica gives an error $\endgroup$ May 12 at 9:18
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I found the issue. The solution was in the examples section of Integrate. The syntax error is with the superscript ^ after \[Integral] in Subscript[\[Integral], 0]^b. Ctrl+% has to be used instead of Ctrl+^.

Correctly:

Assuming[b > 0 && a > 0, \!\(\*SubsuperscriptBox[\(\[Integral]\), \(0\), \(b\)]\(\*FractionBox[SuperscriptBox[\(E\), \(-\*FractionBox[\(a\), \(2 x\)]\)], \(x \((x + 1)\)\)] \[DifferentialD]x\)\)]

This looks long here but copying it back to the Mathematica editor results again in the nice picture posted in the question.

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