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answered A simple problem on first order differential equations
Feb
6
comment A simple problem on first order differential equations
What is the $sen$ function?
Feb
5
revised PDE - three restrictions, wave equation (1 dimension)
added 5 characters in body
Jan
9
answered I have a special solution for the Lane-Emden equation. Can I use it to find the general solution?
Jan
6
comment Second order ODE, first derivative missing
@El Chapo Second order ODE does not have the concept of separable types.
Jan
6
answered Non-linear transport equation with dissipation (PDE) $u_t + uu_x = -cu$
Jan
5
revised Tough NL Diff Eq.
added 194 characters in body
Jan
5
revised Tough NL Diff Eq.
added 689 characters in body; added 96 characters in body
Jan
3
answered Tough NL Diff Eq.
Jan
3
revised Asymptotic behaviour / non-linear ODE
deleted 237 characters in body
Jan
3
answered Asymptotic behaviour / non-linear ODE
Jan
3
answered Problem with $axu_x+byu_y=P(x,y,u)$ type of quasi-linear PDE
Jan
2
comment Tough NL Diff Eq.
Letting $u=1-y$ can reduce the ODE to $u\left(xu''+u'\right)+(u')^4=0$ .
Jan
2
comment Asymptotic behaviour / non-linear ODE
But plugging $y(t)=t^2-\dfrac{1}{a}+B(t)$ con only change the ODE to $\dfrac{d^2B}{dt^2}-\left(\dfrac{dB}{dt}\right)^2-(a+2)t\dfrac{dB}{dt}+2aB=0$ .
Jan
2
comment Asymptotic behaviour / non-linear ODE
@Miguel Atencia The reason is that when $a=0$ , the ODE belongs to the ODE of the form eqworld.ipmnet.ru/en/solutions/ode/ode0347.pdf.
Jan
2
comment Solution of Non-linear ODEs
@Start wearing purple But let $u=\dfrac{dy}{dx}$ can only reduce the ODE to $u^2\dfrac{d^2u}{dy^2}+u\left(\dfrac{du}{dy}\right)^2+k\left(yu\dfrac{du}{dy}-u²‌​+1\right)=0$ .
Dec
28
awarded  Revival
Dec
27
answered Solve this differential equation for $\rho$: $\frac{d}{d\tau}\sqrt{\left(\rho^{3}\frac{d^{2}\rho}{d\tau^{2}}+\rho\right)}=\nu\rho$
Dec
26
revised How to Separate Quasi-Linear PDE
added 73 characters in body
Dec
26
comment Inverse Laplace Transform of a polynomial
Inverse Laplace Transform of the entire functions are often especially difficult to express in nice form, even they obviously exist. Typical examples including the inverse Laplace Transform of $e^{as^2}$ (math.stackexchange.com/questions/169275) . And the inverse Laplace Transform of $s^n$ for natural number $n$ should express in terms of the derivative of the Dirac delta function (math.stackexchange.com/questions/1010927).