4.3 problem 3

Internal problem ID [847]

Book: Elementary differential equations and boundary value problems, 11th ed., Boyce, DiPrima, Meade
Section: Chapter 6.4, The Laplace Transform. Differential equations with discontinuous forcing functions. page 268
Problem number: 3.
ODE order: 2.
ODE degree: 1.

CAS Maple gives this as type [[_2nd_order, _linear, _nonhomogeneous]]

Solve \begin {gather*} \boxed {y^{\prime \prime }+4 y-\sin \relax (t )+\theta \left (-2 \pi +t \right ) \sin \relax (t )=0} \end {gather*} With initial conditions \begin {align*} [y \relax (0) = 0, y^{\prime }\relax (0) = 0] \end {align*}

Solution by Maple

Time used: 0.023 (sec). Leaf size: 25

dsolve([diff(y(t),t$2)+4*y(t)=sin(t)-Heaviside(t-2*Pi)*sin(t-2*Pi),y(0) = 0, D(y)(0) = 0],y(t), singsol=all)
 

\[ y \relax (t ) = -\frac {\left (2 \sin \relax (t )-\sin \left (2 t \right )\right ) \left (\theta \left (-2 \pi +t \right )-1\right )}{6} \]

Solution by Mathematica

Time used: 0.016 (sec). Leaf size: 27

DSolve[{y''[t]+4*y[t]==Sin[t]-UnitStep[t-2*Pi]*Sin[t-2*Pi],{y[0]==0,y'[0]==0}},y[t],t,IncludeSingularSolutions -> True]
 

\begin{align*} y(t)\to \frac {2}{3} \theta (2 \pi -t) \sin ^2\left (\frac {t}{2}\right ) \sin (t) \\ \end{align*}