Possible bug - wrong integral for exp(-k*t)/sqrt(k*t)

Hi All

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. 

Good luck,
Kevin

-- 
                              .*.
Kevin R.J. Ellwood            /V\
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