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Hi, sorry but I have practically no experience with this program and I find it difficult to understand the functions. If you can please explain the various steps to be able to solve the differential equation in the picture. I am interested in deriving the function phi (t), what do you need to know to solve the differential equation? Thanks for your patience   Documento2 DE [explain more] (25).sm (49kb) downloaded 15 time(s).
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Originally Posted by: Ale16595  sorry but I have practically no experience with this program and I find it difficult to understand the functions.
If you can please explain the various steps to be able to solve the differential equation in the picture.
I am interested in deriving the function phi (t), what do you need to know to solve the differential equation?
T The setup to numerical DE solver is same as Mathcad, even superior as it takes the parameters as vector. Use p[1,2,3] for those parameters. Up to what you proposed before: you don't have a DE Those parameters are non-sense as they send the system in the zillion domain. Get that DE from the teacher, a bit of abstract would help.  Documento2 DE [explain more] (25).sm (72kb) downloaded 10 time(s).
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Originally Posted by: Ale16595 ... I am interested in deriving the function phi (t), what do you need to know to solve the differential equation? Thanks for your patience Hi. Usually we want know the ode and it's initial conditions. In your case you have boundary conditions, which can be solved by the shooting method. Hope this helps. motocicleta.sm (49kb) downloaded 21 time(s). motocicleta.pdf (204kb) downloaded 20 time(s).Best regards. Alvaro.
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 2 users thanked Razonar for this useful post.
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on 27/12/2019(UTC), on 27/12/2019(UTC)
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My initial conditions are:
-phi(t = 0) = 0.146
-phi'(t = 0) = 0
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Originally Posted by: Ale16595 My initial conditions are:
-phi(t = 0) = 0.146
-phi'(t = 0) = 0 For a Cauchy problem it's more easy. motocicleta with IC.sm (38kb) downloaded 25 time(s). motocicleta with IC.pdf (137kb) downloaded 25 time(s).Best regards. Alvaro.
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3 users thanked Razonar for this useful post.
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on 27/12/2019(UTC), on 27/12/2019(UTC), on 27/12/2019(UTC)
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Thank you very much,
regards
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This is an offer ... accept/reject ... go back to "square zero"
1. What maths are given/invented: a formula ?
2. From that formula, what is next
So, you have a formula and an objective project,
i.e: a pretty short work sheet not yet circular in the blue.
Jean
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1 user thanked Jean Giraud for this useful post.
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Originally Posted by: Jean Giraud This is an offer ... accept/reject ... go back to "square zero"
1. What maths are given/invented: a formula ?
2. From that formula, what is next
So, you have a formula and an objective project,
i.e: a pretty short work sheet not yet circular in the blue.
Jean I appreciate the advice. I'm trying to learn
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Originally Posted by: Ale16595 I appreciate the advice. I'm trying to learn Just give the formula that you were given. or make an image from source ... learning is after.
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Read more about ODE ... just an initiating visit. These two examples are Cauchy integration. They have no formal symbolic. A discrete integration is possible via the module rkf4(y0,x0,x1,n,f). From there: easy to get the discrete derivative. Jean ODE Cauchy Project.sm (28kb) downloaded 20 time(s).
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Hi, sorry if I bother you again. I'm trying to integrate a function, the function in question is psi''(t) in order to derive psi'(t). I tried using Simpson and Romberg's recursive methods, but without getting a solution. Where am I wrong? PROJECT.sm (70kb) downloaded 18 time(s).
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Originally Posted by: Ale16595 Hi, sorry if I bother you again. I'm trying to integrate a function, the function in question is psi''(t) in order to derive psi'(t). You have phi in your document ... psi is a built-in function. So, if phi''(t) is the 2nd derivative ... then the derivative is simply the integral. To expedite fast: done discrete. If you have questions: please re-post this document. Cheers ... Jean. PROJECT [1].sm (31kb) downloaded 11 time(s).
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Originally Posted by: Jean Giraud You have phi in your document .... in fact you have PSI''(t). Maple does not find an explicit integral. PROJECT [1].sm (22kb) downloaded 15 time(s).
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... lot more maths in there. PROJECT [1].sm (45kb) downloaded 10 time(s).
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Originally Posted by: Ale16595 Hi, sorry if I bother you again. I'm trying to integrate a function, the function in question is psi''(t) in order to derive psi'(t). I tried using Simpson and Romberg's recursive methods, but without getting a solution. Where am I wrong? PROJECT.sm (70kb) downloaded 18 time(s). Hi. You can use any Runge Kutta solver for integration.  Also, you can use SMath int procedure, but it's very (very) slow:  For the theory, remember that you can integrate (with definite integrals) both sides of an equation and get an equality too, which don't work with derivatives. PROJECT.sm (75kb) downloaded 17 time(s).Best regards. Alvaro.
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Hi, I have calculated the function psi '(t) through dn_GearsBDF. But now I can't calculate the ratio in the picture.  The error says, "The matrix must be square" PROJECT.sm (58kb) downloaded 11 time(s).
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Originally Posted by: Ale16595 Hi, I have calculated the function psi '(t) through dn_GearsBDF.
But now I can't calculate the ratio in the picture. Result from numerical ODE solvers is a data set. Generate an interpolation scalar to 'x' ... then plot. @ the end of the document ... more questions: -this one. PROJECT (1).sm (75kb) downloaded 20 time(s).
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