Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Error, (in ODEtools/info) x(t) and x cannot both appear in the given ODE.

  1. Sep 5, 2010 #1
    1. The problem statement, all variables and given/known data

    Hi I am trying to solve a seperable differential equation in Maple

    eqn1:=diff(x(t),t)=3*t^2/sqrt(x);

    But every time I type

    dsolve(eqn1,x(t));

    I get the very hurtfull error from Maple

    "Error, (in ODEtools/info) x(t) and x cannot both appear in the given ODE."

    What am I doing wrong?

    I have changed it to

    eqn1:=diff(x(t),t)=3*t^2/sqrt(x(t)); and Mapple accepted it...

    Is this right?
     
    Last edited: Sep 5, 2010
  2. jcsd
  3. Sep 5, 2010 #2

    HallsofIvy

    User Avatar
    Science Advisor

    "x(t)" and "x" are different symbols. Maple is interpreting "x(t)" as a function of t and "x" as a constant. It appears to Maple that you are using "x" in two different ways and it will not allow that.
     
  4. Sep 5, 2010 #3
    Okay why Hallsoftivy could they go ahead and write this in the error insteed :)

    But thank you :)

    I'm given the differential equation

    [tex]\frac{dx}{dt} = \frac{3t^2}{\sqrt{x}}[/tex]

    without any initial conditions

    the right way to solve this in Maple is the command:
    eqn1:=diff(x(t),t)=3*t^2/sqrt(x(t));

    ??
     
    Last edited: Sep 5, 2010
  5. Sep 5, 2010 #4

    HallsofIvy

    User Avatar
    Science Advisor

    ??? That's what I just said: Maple is telling you that you cannot use the letter "x" in two different meanings and that is how Maple is interpreting what you gave.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook