Re: need help with Plot

*To*: mathgroup at smc.vnet.net*Subject*: [mg88029] Re: need help with Plot*From*: dh <dh at metrohm.ch>*Date*: Tue, 22 Apr 2008 06:28:31 -0400 (EDT)*References*: <fuin33$9oh$1@smc.vnet.net>

Hi, Plot can not deal with a varying number of functions. But as a work around you may define new functions that are zero where you do not want them to draw. As dirty trick, you may instead of returning zero, you may return a symbol. In version 6, this has the effect, that this part is not drawn. Here an example with zero: sol=4 t{Sin[2Pi t],1.2 Sin[ 2.2 Pi t],1.4Sin[ 2.4Pi t], Sin[2.6Pi t]}; {sol1[t_],sol2[t_],sol3[t_],sol4[t_]}=If[#<t,0,#]&/@sol Plot[{sol1[t],sol2[t],sol3[t],sol4[t]},{t,0,5}] Here an example with a symbol (NA): sol=4 t{Sin[2Pi t],1.2 Sin[ 2.2 Pi t],1.4Sin[ 2.4Pi t], Sin[2.6Pi t]}; {sol1[t_],sol2[t_],sol3[t_],sol4[t_]}=If[#<t,NA,#]&/@sol Plot[{sol1[t],sol2[t],sol3[t],sol4[t]},{t,0,5}] hope this helps, Daniel noravanq wrote: > Hi, > > I have the following situation. > > f[z_,t_]=some function > sol=Solve[f[z,t]==0,{z}] > This returns > {{z->sol1[t]},{z->sol2[t]},{z->sol3[t]},{z->sol4[t]}} > I want to plot > Plot[Select[{sol1[t],sol2[t],sol3[t],sol4[t]},#>t&] > But it doesn't plot correctly. Depending on t, Select returns either 2 or 4 values. Plot correctly plots only the sections for which Select returns 2 values (it plots two curves), and doesn't plot anything for the interval for t, in which Select returns 4 values. > Can anyone help to fix this? > > I should also mention, that if I restrict t to only the interval where Select returns 4 values, Plot correctly plots 4 curves. > > Thanks for your help. >