From: SourceForge.net <noreply@so...>  20040310 03:29:04

Bugs item #913239, was opened at 20040309 22:11 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=913239&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: Integral with erf wrong (multiplicative constant off) Initial Comment: integrate(exp(k*t)/sqrt(k*t),t) => SQRT(%PI) k ERF(SQRT(k t)) should be SQRT(%PI) ERF(SQRT(k t)) /k Reported by Kevin Ellwood (kellwood@...) on the Maxima mailing list Tue 2004Mar09 17:38 "I found a few other integrals involving erf() that had similar error in carrying constants through." Macrakis confirms on Maxima 5.9.0 gcl 2.5.0 W2k Fateman reports that this bug is fixed in commercial Macsyma.  Original bug report email I am not to sure if this is a know issue (or if I did something wrong) but I think I found a small bug. I was doing some work with maxima (5.9) in which I was checking my own calculations and I discovered that it got the wrong answer for: (C1) integrate(exp(k*t)/sqrt(k*t),t); (D1) SQRT(%PI) k ERF(SQRT(k t)) The correct answer is: SQRT(%PI) ERF(SQRT(k t)) /k As is shown here: (C3) derivative(sqrt(%PI)/k*erf(sqrt(k*t)),t);  k t %E (D3)  SQRT(k t) Maxima got the hard part correct but failed to carry "k" through the integration correctly. I found a few other integrals involving erf() that had similar error in carrying constants through.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=913239&group_id=4933 