Re: Plotting

*To*: mathgroup at yoda.ncsa.uiuc.edu*Subject*: Re: Plotting*From*: ags at seaman.cc.purdue.edu (Dave Seaman)*Date*: Wed, 27 Feb 91 13:27:44 -0800

mkende at athena.mit.edu writes: >I have a question concerning plotting. I am using release 1.0 on a Next >station. My question is as follows. I have some equation like this: > >1 -2x -y > >which I get from differentiation. I then solve for x in terms of y: > >Solve[% == 0,x] > >to get > >{x->1-y} > --- > 2 1 - y When I do this, I get {{x -> -----}}. The extra set of braces makes a 2 difference. > >I want to plot x as a function of y. If I use the standard plot, i.e. > >Plot[%,{y,0,1}] > >I get an error. Any other way I can think of, namely making a function of the >right hand side of the answer using some variant of "/. %" , still gives the >same error. If you use Plot[x /. %,{y,0,1}], Plot complains that "x /. %" does not evaluate to a real number. That's because you get {(1-y)/2}, which is a list, rather than a real number. >Is there any way of plotting (1-y)/2 from the solution without having to simply >retype it into the Plot command? You can use Plot[First[x /. %],{y,0,1}] Dave Seaman