dsolve - Unable to find explicit solution
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Jakub Jedrzejczyk
am 7 Mär. 2018
Beantwortet: Om Yadav
am 24 Apr. 2020
Hi there! I'm trying to solve differetial equation:
Unfortunately result of code:
gamma = 1.4
P0 = 1
Pe = 9.4
R = 0.168
syms S P(t)
eqn = diff(P,t) == (3/R)*S*(Pe-P0)*((P/P0)^(1/gamma))*(1-((P0/P)^(1/gamma))*((Pe-P)/(Pe-P0)))^(2/3);
dsolve(eqn)
is:
Warning: Unable to find explicit solution. Returning implicit solution instead.
> In dsolve (line 208)
In Untitled (line 7)
ans =
1
1/root(z^6 + z^5 + z^4 + z^3 + z^2 + (5*z)/47 + 5/47, z, 1)^7
solve(int(42^(2/3)/(P^(5/7)*(5*P^(2/7) - 47/P^(5/7) + 42)^(2/3)), P, 'IgnoreSpecialCases', true, 'IgnoreAnalyticConstraints', true) - 150*S*t - C11 == 0, P)
What i'm doing wrong?
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Akzeptierte Antwort
Walter Roberson
am 7 Mär. 2018
Nothing. It just does not have a closed form solution that can reasonably be found.
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Weitere Antworten (2)
Jakub Jedrzejczyk
am 7 Mär. 2018
8 Kommentare
Nenad Vujovic
am 25 Jan. 2020
Can someone solve this:
>> syms y(t);
dsolve('Dy=sin(t)*cos(t)+2-(y*cos(t))')
ans =
C5*exp(-sin(t)) + exp(-sin(t))*int((exp(sin(t))*(sin(2*t) + 4))/2, t, 'IgnoreAnalyticConstraints', true)
Walter Roberson
am 25 Jan. 2020
That is the solution. Most integrals do not have closed form solutions.
Om Yadav
am 24 Apr. 2020
We got it very well that closed formula for my problem does not exist. The question is, how to get a numerical solution using dsolve?
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