|Re: integration on 39gII emulator|
Message #21 Posted by Wes Loewer on 1 June 2013, 2:45 a.m.,
in response to message #20 by Tim Wessman
Has to do with an internal problem when converting the result back from the CAS with a negative exponent (which gets dropped during the conversion...)
The internal result there is actually -1.93772545304E-12.
Ah. That would explain the unusual graph of
6.2 < X < 6.4
0 < Y < 15
But it doesn't explain the problem with the second integral.
Let F(X)=5*e^(-x) - 1
F(A)=0, A = 1.60943791243
integral(ABS(F(X)),X,1,4)=1.71209957, but 39gII reports 2.50436197717, which coincidentally is equal to 2*ABS(integral(F(X),X,1,4)). Using integral(ABS(F(X)),X,1,A)+integral(ABS(F(X)),X,A,4) gives the correct answer.
It seems that the ABS( ) is confusing the CAS.