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Re: Manipulate a Plot of Evaluate DSolve
*To*: mathgroup at smc.vnet.net
*Subject*: [mg127504] Re: Manipulate a Plot of Evaluate DSolve
*From*: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>
*Date*: Mon, 30 Jul 2012 22:12:56 -0400 (EDT)
*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com
*Delivered-to*: l-mathgroup@wolfram.com
*Delivered-to*: mathgroup-newout@smc.vnet.net
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Hi,
I'm trying to Manipulate a Plot of a quite difficult function which involves solving a differential equation, but cannot be solved analytically.
To try to simplify the example and simulate it, let's assume that we have the following function:
func[coef_] = {{y -> Function[{x}, DSolve[y'[x] == Cos[coef *x], y, x]]}}
Manipulate[Plot[{{Evaluate[y[x] /. func[coef] /. C[1] -> {Range[-5, 0]}]}},{x, -10, 10}], {{coef , 1}, 0.1, 5}]
I get an error: DSolve::dsvar: "-9.99959 cannot be used as a variable"
I think that this is because Manipulate assigns a value to x (= -9.99959)BEFORE solving the DSolve, even though to avoid it I'm using the Evaluate function, which should process the function before assigning a value to x.
But the thing is that the "coef" to be Manipulated is at the same "level" as the x in the Manipulate block, so probably if I need the coef to solve the DSolve, I also have the x that gives me an error.
Is there any workaround? I guess I'm not understanding properly how Mathematica processes these simple expressions.
Thanks, Juan
Hi, Juan,
Try this:
Manipulate[
Plot[Evaluate[
y[x] /. DSolve[{y'[x] == Cos[coef*x]}, y, x] /.
C[1] -> Range[-5, 0]], {x, -10, 10}], {{coef, 1}, 0.1, 5}]
Have fun, Alexei
Alexei BOULBITCH, Dr., habil.
IEE S.A.
ZAE Weiergewan,
11, rue Edmond Reuter,
L-5326 Contern, LUXEMBOURG
Office phone : +352-2454-2566
Office fax: +352-2454-3566
mobile phone: +49 151 52 40 66 44
e-mail: alexei.boulbitch at iee.lu
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