Integral with Gammafunction does not work

11202023, 07:35 PM
Post: #1




Integral with Gammafunction does not work
I tried to integrate ln(X)*Gamma(X) from 0.2 to 0.8 in Home mode.
The function to integrate was (LN(X)*(X1)!). You can get the result for X = 0.2: 7.38868 For X = 0.5: 1,22857 For X = 0.8: 0.25979 You can graph the function which is totally smooth. But if you try to integrate the function from 0.2 to 0.8 you get "Fehler: Ungültige Eingabe" ("Error: Invalid Input"). If I integrate only the function (X1)! from 0.2 to 0.8 it works. Result is 1.245887. I work with Software version 2.1.14730, Hardwareversion D, CASversion 1.5.0. Any idea why LN(X)*(X1)! cannot be integrated? 

11202023, 07:52 PM
Post: #2




RE: Integral with Gammafunction does not work
It seems it is a conversion problem between Home and CAS. Inside the debugger, I can see that the postfixed ! (factorial) function is wrongly translated to a prefixed ! function (perhaps the not function)
ln(X)*!(X) The same integral is correctly evaled inside CAS. 

11202023, 11:43 PM
Post: #3




RE: Integral with Gammafunction does not work
Thank you Parisse.
Yes, in CAS mode it works. This being a purely numerical problem I did not think of using CAS mode. It seems it has something to do with the LN function as well. If I make the integral from 0.2 to 0.8 of SIN(X) * (X1)! using RAD in Home mode I get the result 0.514558. This works as well in CAS mode. 

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