Direction Fields

*To*: mathgroup at smc.vnet.net*Subject*: [mg2079] Direction Fields*From*: nprive at mbhs.edu (Nikki Prive )*Date*: Fri, 29 Sep 1995 01:12:14 -0400*Organization*: Montgomery Blair HS

I am using a Power Mac 6100/60 with Mathematica 2.2.2 in an attempt to create direction fields. My textbook says that to make one, I must first type ">>Graphics`PlotField`. However, I get two errors when I do this: PlotVectorField::shdw: Warning: Symbol PlotVectorField appears in multiple contexts {Graphics`PlotField`,Global`}; definitions in context Graphics`PlotField` may shadow or be shadowed by other defintions. ScaleFunctions::shdw: Warning:Symbol ScaleFunctions appears in multiple contexts {Graphics`PlotField`,Global`}; definitions in context Graphics`PlotField` may shadow or be shadowed by other defintions then, when I try to plot a direction field, PlotVectorField[{1,y^2-xy},{x,0,20},{y,0,20},Axes->True,ScaleFunction ->(1&),Ticks->None,Frame->True], mathematica simply echos this back to me without making a plot. When I later try again, >>Graphics`PlotField` I get Syntax::sntxf:">>Graphics`PlotField" cannot be followed by "`". How can I get Mathematica to make thses direction fields? I tried typing imn verbatim an example from my textbook and received the same result, so I assume it is not my equation but something wrong with the computer or Mathematica's setup. Help! Thanks in advance, Nikki Prive' nprive at wam.umd.edu