Re: How do I get a DSolve'd function

*To*: mathgroup at smc.vnet.net*Subject*: [mg54429] Re: How do I get a DSolve'd function*From*: Curt Fischer <tentrillion at gmail.NOSPAM.com>*Date*: Sun, 20 Feb 2005 00:09:48 -0500 (EST)*References*: <cv6t29$6su$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Skirmantas wrote: > I hope this is the last question for now. > > I can solve a differential equation and plot it by doing something > like this: > > sol=DSolve[{f'[x]==-3f[x],f[0]==10},f,x] > Plot[f/.sol,{x,0,10}] > > But how do I get the function f[x] itself? I want to be able to input > f[x] and get its definition. Or do Plot[f[x],{x,0,10}]. Or define > y[x_]:=f[x]^2. > > f[x]/.sol or f[x_]:=f[x]/.sol or f[x_]:=sol[[n,n,n]] do not work. > > What if the solution is a function with many variables, say u[x,y,z]? > What's the correct way to "get" it? In[4]:= sol=DSolve[{f'[x]\[Equal]-3f[x],f[0]\[Equal]10},f,x];sol//InputForm Out[4]//InputForm= {{f -> Function[{x}, 10/E^(3*x)]}} In[2]:= g[y_]:=f[x]/.sol[[1]]/.x -> y In[5]:= g[1]//InputForm Out[5]//InputForm= 10/E^3 -- Curt Fischer