MaplePrimes - answers and comments on Question, Warning, expecting Range variable k blablabla... while trying to plot

Input to plot?

Preben Alsholm — Thu, 31 Jan 2013 22:49:13 Z

As the following works, I wonder what the actual input to plot was.

f:=HeunG(3,-9/2+3/4*I*k-3/4*k^2,-1+1/2*I*k,-1/2+1/2*I*k,1/2,1+I*k,1/2);
f1:=diff(f,k);
plots:-complexplot(f1,k=0..2);

If we let F be the result you posted above then attempts to evaluate results in an error:

evalf(eval(F,k=1.2345));
Error, (in simpl/abs) abs is not differentiable at non-real arguments

So the problem seems to be the presence of abs in your input and as a result also abs(1,..) in F:

indets(F,specfunc(anything,abs));

Something can be done

Markiyan Hirnyk — Thu, 31 Jan 2013 23:14:38 Z

How about this?

Download argument.mw

The warning is unrelated

Carl Love — Thu, 31 Jan 2013 23:40:29 Z

To expand on what Preben said, what plot said is only a warning, not an error, and it turns out to be unrelated to why you didn't get a plot. If you apply argument or abs after taking the derivative, it plots fine:

f:= HeunG(3,-9/2+3/4*I*k-3/4*k^2,-1+1/2*I*k,-1/2+1/2*I*k,1/2,1+I*k,1/2):
f1:=diff(f,k):
plot([argument,abs](f1), k= 0..2);

Edit: I realize that this plot is not the same as the function you want. I'm just illustrating that the failure to plot is unrelated to the warning message.

first of all thank you for all your answers...

digerdiga — Fri, 01 Feb 2013 03:15:08 Z

first of all thank you for all your answers... i dont quite get why maple cant differentiate an argument (same as with abs apparently) but here is how i solved it:

If i call the function which contains the HeunG functions i know it has some complex value say

Therefore

Which plots the right result.I can show you what i meant if im back at uni. Unfortunately for values k larger than 25/30 the function doesnt have the right behaviour anymore. I guess it is due to inaccuracies. Still very unfortunate.

i havent changed my notation. if you are

digerdiga — Fri, 01 Feb 2013 19:25:44 Z

i havent changed my notation.

if you are refering to the -ln(2)*k term i have eliminated this term by the factor in the wronskian because the argument of yg would otherwise be discontinuous..dont worry about it.

added a .mw file

Download mapleprimes.mw mapleprimes.mw

argument

Markiyan Hirnyk — Thu, 31 Jan 2013 23:29:04 Z

Have you paid attention to the argument in the question?

PS. BTW, using your notation for F,

> evalf(eval(F, k = 0));
-0.6931471806