Problems with plotdf



Actually I think I meant if the diff eq was 

'diff(y,x,2)+x^2*y=e*y

'diff(y,x,2)+x^4*y=e*y

I want to see the direction field of de/dx if that is possible.

Rich


 ------------Original Message------------
From: "Richard Hennessy"<rvh2007 at comcast.net>
To: "Walter Wegscheider" <walter.wegscheider at ph-noe.ac.at>, maxima at math.utexas.edu
Date: Fri, Jun-20-2008 1:18 PM
Subject: Re: [Maxima] Problems with plotdf

I am not having any bugs in plotdf yet but I have a different issue.  I want to see the direction field of 

'diff(y,x,2)+x^4*y=0 or 'diff(y,x,2)+x^2*y=0 but I don't understand the documentation so I can't figure out what to enter to get that.

Can anyone help?

Thanks,

Rich





 ------------Original Message------------
From: Walter Wegscheider <walter.wegscheider at ph-noe.ac.at>
To: maxima at math.utexas.edu
Date: Fri, Jun-20-2008 3:57 AM
Subject: Problems with plotdf

I have Problems with Direction Fields (Windows XP SP2, Maxima 5.15.0, 
wxMaxima 0.7.5)
If I try to plot Inputs like (see Maxima Manual)

plotdf(x-y^2,[xfun,"sqrt(x);-sqrt(x)"], 
trajectory_at,-1,3],[direction,forward],
  [y,-5,5], [x,-4,16])$

including [xfun, ...] I always get failures - without xfun 
everything is working fine.

Thanks and kind regards
Walter Wegscheider


Failure description in OpenMath:

Input file has syntax errors
can't read "_WinInfo.dfplot(nolegend)": no such element in array
    while executing
"set _WinInfo[set win]($var)"
    (procedure "oget" line 3)
    invoked from within
"oget .dfplot nolegend"
    invoked from within
"set nolegend [oget .dfplot nolegend]"
    ("uplevel" body line 1)
    invoked from within
"uplevel 1 set  $v \[oget $win $v\]"
    (procedure "makeLocal" line 3)
    invoked from within
"makeLocal $win  c nolines nolegend plotpoints  pointsize 
    bargraph linewidth"
    (procedure "drawPlot" line 2)
    invoked from within
"drawPlot $win [list $ans] -tags [list [concat $tags line[oget $win 
curveNumber]]]  -fill $color -label $label"
    ("foreach" body line 41)
    invoked from within
"foreach {xvalues yvalues} [lrange $d 1 end] {
		    # puts "xvalues=$xvalues"
		    #puts "here:$curvenumber,[oget $win curveNumber]"
		    oset $win ..."
    ("xversusy" arm line 6)
    invoked from within
"switch  $type {
	    xversusy {
		#puts "starting .. [oget $win curveNumber]"
		set curvenumber [oget $win curveNumber]
		# the data can be multiple l..."
    (procedure "redraw2dData" line 13)
    invoked from within
"redraw2dData $win -tags path"
    (procedure "replotdf" line 24)
    invoked from within
"replotdf $win"
    (procedure "plotdf" line 28)
    invoked from within
"plotdf -dydx "x-1.0*y^2" -xfun {sqrt(x);-sqrt(x)} -trajectory_at 
{-1 3} -direction {forward} -ycenter {0} -yradius {5} -xcenter {6} 
-xradius {10} " 
("eval" body line 1)
    invoked from within
"eval $inputdata"
_______________________________________________
Maxima mailing list
Maxima at math.utexas.edu
http://www.math.utexas.edu/mailman/listinfo/maxima

_______________________________________________
Maxima mailing list
Maxima at math.utexas.edu
http://www.math.utexas.edu/mailman/listinfo/maxima