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RE: Plot Complex Interpol .Func.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg9590] RE: [mg9561] Plot Complex Interpol .Func.
  • From: jmthomas <jmthomas at cybercable.tm.fr>
  • Date: Thu, 13 Nov 1997 23:24:02 -0500
  • Sender: owner-wri-mathgroup at wolfram.com

Check the syntax for ParametricPlot: you need two (real) arguments:
ParametricPlot[{function1, function2},{param,min,max}] In your case you
can use:
{r[a_],i[a_]}={Re[(f/.First at soln)[a],Im[ etc, where Re and Im split 
the complex value into two real arguments, then
ParametricPlot[{r at a,i at a,{a,min, max}] Hope this helps


----------------------------------------------- Jean-Marie THOMAS
Conseil et Audit en Ingnierie de Calcul jmthomas at cybercable.tm.fr
www.cybercable.tm.fr/~jmthomas

-----Original Message-----
From:	Jim Leddon [SMTP:jleddon at cyberramp.net] To: mathgroup at smc.vnet.net
Sent:	Thursday, November 13, 1997 7:40 AM To:	mathgroup at smc.vnet.net
Subject:	[mg9561] Plot Complex Interpol .Func.

I am trying to solve the schrodinger equation  as follows and I want to
be able to plot the resulting interpolating function (which should
contain complex values).

In[6]:=Schrodinger[V_,A_] := D[f[a],{a,2}] + (V - A)f[a]]

In[7]:= R[x_,y_] := x + I y

In[8]:= V[R_,a_] :=
  		R[1,2](-1/(Cos[a]  - Sin[a]) -1/Sin[a] + 1/Cos[a])

In[9]:= eq1 = 0 == Schrodinger[V[R,a],-900] Out[9]=
0==f[a] (900 + (1 +
2 I) (-Csc[a] + Sec[a] -
                  1/(Cos[a] - Sin[a])) + f''[a]

In[10]:=  soln =NDSolve[{eq1, f[0.00005] ==0, f'[0.00005] 
==.5},
      			f, {a, 0.00005, 0.785348}][[1]] Out[10]=
	{f->InterpolatingFunction[{{0.00005,0.785348}},"<>"]}

In[11]:= ParametricPlot[f /. soln[[1]], {a, 0.00005, 1}]

The error message I got at this point was:
	function f/. soln[[1]] cannot be compiled; plotting will proceed..  f/.
soln[[1]] does not evaluate to a real pair of numbers
		at a =0.000050041664...., etc.

What went wrong ? How can I plot the interpolating function?

Thanks in advance for your help!
Debbie Leddon
jleddon at cyberramp.net




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