MathGroup Archive 2004

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: DSolve question


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


  • Prev by Date: RE: Joining 2D arrays
  • Next by Date: partition of 2D arrray
  • Previous by thread: DSolve question
  • Next by thread: Re: Re: DSolve question