Re: Scale ContourPlot axes

*To*: mathgroup at smc.vnet.net*Subject*: [mg67404] Re: [mg67393] Scale ContourPlot axes*From*: "Carl K. Woll" <carlw at wolfram.com>*Date*: Thu, 22 Jun 2006 06:21:21 -0400 (EDT)*References*: <200606210613.CAA08944@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Nick wrote: > Hi there, > > I have a ContourPlot with axes of parameters "a" and "b" and contours > of a function "f". Obviously the parameters, "a" and "b" are varied > within defined boundary conditions to calculate "f". > > My question: Is it possible to convert the axes to a log scale (within > ConoutPlot) while maintaining the normal values of these parameters, > ie. scale the linear axes to a log scale without converting to log > units? > > I haven't been able to find a way of acheiving this and would really > appreciate any ideas out there. > > Nick You need to do the scaling by hand, using FrameTicks. Here is a simple example: f[x_,y_]:=x^2+Log[y]^2 Let's plot this over the range -3<x<3 and Exp[-3]<y<Exp[3] so that we get a nice circle. xmin=-3; xmax=3; ymin=Exp[-3]; ymax=Exp[3]; Now, we want to use ContourPlot with Log scaling. So ContourPlot[f[x, 10^z],{x,xmin,xmax},{z,Log[10,ymin],Log[10,ymax]}] will produce the desired plot, but with ticks labeled using the log scale. We fix the ticks by using FrameTicks. Here is a function that produces a table of {linear,log} values: tickfunction[min_,max_]:= Flatten[ N@Table[ {e+Log[10,d],d 10^e}, {e,Floor[Log[10,min]],Ceiling[Log[10,max]]}, {d,1,5,4} ], 1 ] So, the following produces the desired plot: ContourPlot[f[x,10^z],{x,xmin,xmax},{z,Log[10,ymin],Log[10,ymax]}, FrameTicks->{Automatic,tickfunction[ymin,ymax]}] Carl Woll Wolfram Research

**References**:**Scale ContourPlot axes***From:*"Nick" <nick.dale.burns@gmail.com>