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how do I get rid of this msg Error, unable to match delimiters

Posted on 2008-09-07 13:00 By Zak (4)
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Hey im trying to solve this equation of 2 order but its keeping giving me that starange error.

del:=(x^((1/(3)))*y^((2/(3)))(x)+x)*diff(x)+(x^((2/(3)))*y^((1/(3)))(x)+y(x))*diff(y(x))=0;
 

Can someone giude me on how to solve it

 

thanks.

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AS you see I change the

Comment on 2008-09-07 13:05 from Zak (4)

AS you see I change the order of the brachet but its still givin me an error

> f:=(x^((1/(3)))*y^((2/(3)))(x)+x)*diff(x)+(x^((2/(3)))*y^((1/(3)))(x); +y(x)*diff(y(x))=0;

Error, invalid input: diff expects 2 or more arguments, but received 1
 

Doug Meade's picture

A guess, and some ideas

Comment on 2008-09-08 14:17 from Doug Meade (Maple Rating 4 715)

It appears to me that you have a differential equation of order 1. I'm guessing that your original equation involves the differentials "dx" (diff(x)) and "dy" (diff(y(x)). Maple does not work with differentials; divide by dx and the equation can be written as:

ode := (x^(1/3)*y(x)^(2/3)+x)+(x^(2/3)*y(x)^(1/3)+y(x))*diff(y(x),x)=0;
        (1/3)     (2/3)       / (2/3)     (1/3)       \ / d      \    
       x      y(x)      + x + \x      y(x)      + y(x)/ |--- y(x)| = 0
                                                        \ dx     /   

Note that you have to write y(x)^(1/3), not (y^(1/3)(x)).

Now, what do you want to do with this equation? Do you have an initial condition?

The equation is homogeneous. This might allow you to simplify it a little.

Why do you refer to the equation as having "order 2"?

Doug

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Robert Israel's picture

diff

Comment on 2008-09-07 13:42 from Robert Israel (Maple Rating 4 1431)

The expression you posted does not give that error, which would indicate that you made a mistake in parentheses.  In the Standard interface, 1d input has automatic matching of delimiters,: if you put the cursor after a "(" or ")", the corresponding ")" or "(" will have a little box around it. 

The error "invalid input: diff expects 2 or more arguments, but received 1" means pretty much what it says: you have to tell the differentiation command diff what variable(s) to differentiate with respect to.  For example, you might use diff(y(x),x) for diff(y(x),x), but diff(y(x)) without a second argument is incorrect.

There is something else strange about your expression: I suspect that you didn't really mean y^((2/(3)))(x), which tells Maple to evaluate the "function" 2/3 at x (the result of that being 2/3), but rather y(x)^(2/3).

 

 

What are you trying to do?

Comment on 2008-09-07 17:26 from arijin (6)

Your original command needs an argument telling Maple which variable you are differentiating with respect to. That has nothing to do with your original error, though, which implies your parentheses are not matching up correctly.

I would ask, though, what, exactly it is you are trying to solve. You have so many parentheses in there that it is confusing to try to decipher the original problem.

If you are running a recent version of Maple, it might help you to right click (or ctrl-click, if you have a Mac with a one-button mouse), and scroll down within the pop-up menu to conversions, then select convert-to 2d Math input. That will show you exactly what your input would look like as an expression, rather than a complicated input line.

Doing this might help you figure out your problem. (you can also edit it within the 2-d input it gives you).

I just did that with your input, and the expression it gave me was understandable, aside from the fact that the differentiation symbol was missing a denominator... However, I'm not sure if the expression actually is what you were trying to input.

If you have a version that supports this feature, I recommend you try it for yourself in order to make any corrections you need.

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