Re: Re: DSolve question

*To*: mathgroup at smc.vnet.net*Subject*: [mg49164] Re: [mg49155] Re: DSolve question*From*: James Smith <jasmith at cim.mcgill.ca>*Date*: Tue, 6 Jul 2004 03:33:23 -0400 (EDT)*References*: <200407050854.EAA14799@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Starting a fresh session was the key to solving this problem. thanks to everyone who pointed it out. :-) -James On 5-Jul-04, at 4:54 AM, Bill Rowe wrote: > On 7/2/04 at 2:01 AM, jasmith at cim.mcgill.ca (James A. Smith) wrote: > >> Being a Mathematica novice, I'm confused by an error generated when >> I modify the following differential equation example: > >> Input 1: DSolve[y'[x] == 2 a x, y[x], x] Output 1: {{y[x] -> a x^2 >> + C[1]}} > >> This is fine. But why does the following produce an error, since >> all I am doing is replacing the independent "x" variable with "t" >> and the dependent "y" variable with "x": > >> Input 2: DSolve[x'[t] == 2 a t, x[t], t] (error) DSolve::dvnoarg: >> The function x appears with no arguments. > > DSolve[Derivative[1][y][x] == 2*a*x, y[x], x] > {{y[x] -> a*x^2 + C[1]}} > > DSolve[Derivative[1][x][t] == 2*a*t, x[t], t] > {{x[t] -> a*t^2 + C[1]}} > > $Version > "4.2 for Mac OS X (August 22, 2002)" > > As you can see, it seems to work fine for me. > > Here, all I did was copy and paste from your post to Mathematica in a > fresh session. > -- > To reply via email subtract one hundred and four > > James Andrew Smith PhD Candidate, Mechanical Engineering Ambulatory Robotics Lab McGill University Web: www.cim.mcgill.ca/~jasmith Phone: 514-398-8054

**References**:**Re: DSolve question***From:*Bill Rowe <readnewsciv@earthlink.net>