Second Order IVPs - Maple Help
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ODE Steps for Second Order IVPs

 

Overview

Examples

Overview

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This help page gives a few examples of using the command ODESteps to solve second order initial value problems.

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See Student[ODEs][ODESteps] for a general description of the command ODESteps and its calling sequence.

Examples

withStudent:-ODEs:

ivp1diffyx,x,xdiffyx,xxexpx=0,evaldiffyx,x,x=0=0,y0=1

ivp1ⅆ2ⅆx2yxⅆⅆxyxxⅇx=0,ⅆⅆxyxx=0|ⅆⅆxyxx=0=0,y0=1

(1)

ODEStepsivp1

Let's solveⅆ2ⅆx2yxⅆⅆxyxxⅇx=0,ⅆⅆxyxx=0|ⅆⅆxyxx=0=0,y0=1Highest derivative means the order of the ODE is2ⅆ2ⅆx2yxIsolate 2nd derivativeⅆ2ⅆx2yx=ⅆⅆxyx+xⅇxGroup terms withyxon the lhs of the ODE and the rest on the rhs of the ODE; ODE is linearⅆ2ⅆx2yxⅆⅆxyx=xⅇxCharacteristic polynomial of homogeneous ODEr2r=0Factor the characteristic polynomialrr1=0Roots of the characteristic polynomialr=0,11st solution of the homogeneous ODEy1x=12nd solution of the homogeneous ODEy2x=ⅇxGeneral solution of the ODEyx=C1y1x+C2y2x+ypxSubstitute in solutions of the homogeneous ODEyx=C1+C2ⅇx+ypxFind a particular solutionypxof the ODEUse variation of parameters to findypherefxis the forcing functionypx=y1xy2xfxWy1x,y2xⅆx+y2xy1xfxWy1x,y2xⅆx,fx=xⅇxWronskian of solutions of the homogeneous equationWy1x,y2x=1ⅇx0ⅇxCompute WronskianWy1x,y2x=ⅇxSubstitute functions into equation forypxypx=xⅇxⅆx+ⅇxxⅆxCompute integralsypx=ⅇx1x+12x2Substitute particular solution into general solution to ODEyx=C1+C2ⅇx+ⅇx1x+12x2Check validity of solutionyx=_C1+_C2ⅇx+ⅇx1x+12x2Use initial conditiony0=11=_C1+_C2+1Compute derivative of the solutionⅆⅆxyx=_C2ⅇx+ⅇx1x+12x2+x1ⅇxUse the initial conditionⅆⅆxyxx=0|ⅆⅆxyxx=0=00=_C2Solve for_C1and_C2_C1=0,_C2=0Substitute constant values into general solution and simplifyyx=ⅇxx22x+22Solution to the IVPyx=ⅇxx22x+22

(2)

ivp2diffyx,x,x+5diffyx,x2yx=0,evaldiffyx,x,x=1=3,y1=1

ivp2ⅆ2ⅆx2yx+5ⅆⅆxyx2yx=0,ⅆⅆxyxx=1|ⅆⅆxyxx=1=−3,y1=1

(3)

ODEStepsivp2

Let's solveⅆ2ⅆx2yx+5ⅆⅆxyx2yx=0,ⅆⅆxyxx=1|ⅆⅆxyxx=1=−3,y1=1Highest derivative means the order of the ODE is2ⅆ2ⅆx2yxDefine new dependent variableuux=ⅆⅆxyxComputeⅆ2ⅆx2yxⅆⅆxux=ⅆ2ⅆx2yxUse chain rule on the lhsⅆⅆxyxⅆⅆyuy=ⅆ2ⅆx2yxSubstitute in the definition ofuuyⅆⅆyuy=ⅆ2ⅆx2yxMake substitutionsⅆⅆxyx=uy,ⅆ2ⅆx2yx=uyⅆⅆyuyto reduce order of ODEuyⅆⅆyuy+5uy2y=0Separate variablesⅆⅆyuyuy=5yIntegrate both sides with respect toyⅆⅆyuyuyⅆy=5yⅆy+C1Evaluate integrallnuy=5lny+C1Solve foruyuy=ⅇC1y5Solve 1st ODE foruyuy=ⅇC1y5Revert to original variables with substitutionuy=ⅆⅆxyx,y=yxⅆⅆxyx=ⅇC1yx5Separate variablesⅆⅆxyxyx5=ⅇC1Integrate both sides with respect toxⅆⅆxyxyx5ⅆx=ⅇC1ⅆx+C2Evaluate integralyx66=ⅇC1x+C2Solve foryxyx=6ⅇC1x+6C216,yx=6ⅇC1x+6C216Check validity of solutionyx=6ⅇc__1x+6_C216Use initial conditiony1=11=6ⅇc__1+6_C216Compute derivative of the solutionⅆⅆxyx=ⅇc__16ⅇc__1x+6_C256Use the initial conditionⅆⅆxyxx=1|ⅆⅆxyxx=1=−3−3=ⅇc__16ⅇc__1+6_C256Solve forc__1and_C2c__1=ln3+Iπ,_C2=196Substitute constant values into general solution and simplifyyx=18x+1916Check validity of solutionyx=6ⅇc__1x+6_C216Use initial conditiony1=11=6ⅇc__1+6_C216Compute derivative of the solutionⅆⅆxyx=ⅇc__16ⅇc__1x+6_C256Use the initial conditionⅆⅆxyxx=1|ⅆⅆxyxx=1=−3−3=ⅇc__16ⅇc__1+6_C256Solve forc__1and_C2The solution does not satisfy the initial conditionsSolution to the IVPyx=18x+1916

(4)

ivp3diffyx,x,xdiffyx,x6yx=0,evaldiffyx,x,x=1=a,y1=0

ivp3ⅆ2ⅆx2yxⅆⅆxyx6yx=0,ⅆⅆxyxx=1|ⅆⅆxyxx=1=a,y1=0

(5)

ODEStepsivp3

Let's solveⅆ2ⅆx2yxⅆⅆxyx6yx=0,ⅆⅆxyxx=1|ⅆⅆxyxx=1=a,y1=0Highest derivative means the order of the ODE is2ⅆ2ⅆx2yxCharacteristic polynomial of ODEr2r6=0Factor the characteristic polynomialr+2r3=0Roots of the characteristic polynomialr=−2,31st solution of the ODEy1x=ⅇ2x2nd solution of the ODEy2x=ⅇ3xGeneral solution of the ODEyx=C1y1x+C2y2xSubstitute in solutionsyx=C1ⅇ2x+C2ⅇ3xCheck validity of solutionyx=c__1ⅇ2x+_C2ⅇ3xUse initial conditiony1=00=c__1ⅇ−2+_C2ⅇ3Compute derivative of the solutionⅆⅆxyx=2c__1ⅇ2x+3_C2ⅇ3xUse the initial conditionⅆⅆxyxx=1|ⅆⅆxyxx=1=aa=2c__1ⅇ−2+3_C2ⅇ3Solve forc__1and_C2c__1=a5ⅇ−2,_C2=a5ⅇ3Substitute constant values into general solution and simplifyyx=aⅇ22xⅇ3+3x5Solution to the IVPyx=aⅇ22xⅇ3+3x5

(6)

ivp4x2diffyx,x,x4xdiffyx,x+2yx=0,evaldiffyx,x,x=1=10,y1=1

ivp4x2ⅆ2ⅆx2yx4xⅆⅆxyx+2yx=0,ⅆⅆxyxx=1|ⅆⅆxyxx=1=10,y1=−1

(7)

ODEStepsivp4

Let's solvex2ⅆ2ⅆx2yx4xⅆⅆxyx+2yx=0,ⅆⅆxyxx=1|ⅆⅆxyxx=1=10,y1=−1Highest derivative means the order of the ODE is2ⅆ2ⅆx2yxIsolate 2nd derivativeⅆ2ⅆx2yx=2yxx2+4ⅆⅆxyxxGroup terms withyxon the lhs of the ODE and the rest on the rhs of the ODE; ODE is linearⅆ2ⅆx2yx4ⅆⅆxyxx+2yxx2=0Multiply by denominators of the ODEx2ⅆ2ⅆx2yx4xⅆⅆxyx+2yx=0Make a change of variablest=lnxSubstitute the change of variables back into the ODECalculate the1stderivative ofywith respect tox, using the chain ruleⅆⅆxyx=ⅆⅆtytⅆⅆxtxCompute derivativeⅆⅆxyx=ⅆⅆtytxCalculate the2ndderivative ofywith respect tox, using the chain ruleⅆ2ⅆx2yx=ⅆ2ⅆt2ytⅆⅆxtx2+ⅆ2ⅆx2txⅆⅆtytCompute derivativeⅆ2ⅆx2yx=ⅆ2ⅆt2ytx2ⅆⅆtytx2Substitute the change of variables back into the ODEx2ⅆ2ⅆt2ytx2ⅆⅆtytx24ⅆⅆtyt+2yt=0Simplifyⅆ2ⅆt2yt5ⅆⅆtyt+2yt=0Characteristic polynomial of ODEr25r+2=0Use quadratic formula to solve forrr=5±172Roots of the characteristic polynomialr=52172,52+1721st solution of the ODEy1t=ⅇ52172t2nd solution of the ODEy2t=ⅇ52+172tGeneral solution of the ODEyt=C1y1t+C2y2tSubstitute in solutionsyt=C1ⅇ52172t+C2ⅇ52+172tChange variables back usingt=lnxyx=C1ⅇ52172lnx+C2ⅇ52+172lnxSimplifyyx=x52x172C1+x172C2Check validity of solutionyx=x52x172c__1+x172_C2Use initial conditiony1=−1−1=c__1+_C2Compute derivative of the solutionⅆⅆxyx=5x32x172c__1+x172_C22+x52x17217c__12x+x17217_C22xUse the initial conditionⅆⅆxyxx=1|ⅆⅆxyxx=1=1010=5c__12+5_C2217c__12+17_C22Solve forc__1and_C2c__1=12251734,_C2=12+251734Substitute constant values into general solution and simplifyyx=x5225x1721725x17217+17x172+17x17234Solution to the IVPyx=x5225x1721725x17217+17x172+17x17234

(8)

ivp5x2+1diffyx,x,xxdiffyx,x+yx=0,evaldiffyx,x,x=2=1,y2=1

ivp5x2+1ⅆ2ⅆx2yxxⅆⅆxyx+yx=0,ⅆⅆxyxx=2|ⅆⅆxyxx=2=−1,y2=1

(9)

ODEStepsivp5

Let's solvex2+1ⅆ2ⅆx2yxxⅆⅆxyx+yx=0,ⅆⅆxyxx=2|ⅆⅆxyxx=2=−1,y2=1Highest derivative means the order of the ODE is2ⅆ2ⅆx2yxIsolate 2nd derivativeⅆ2ⅆx2yx=yxx21xⅆⅆxyxx21Group terms withyxon the lhs of the ODE and the rest on the rhs of the ODE; ODE is linearⅆ2ⅆx2yx+xⅆⅆxyxx21yxx21=0Multiply by denominators of ODEx2+1ⅆ2ⅆx2yxxⅆⅆxyx+yx=0Make a change of variablesθ=arccosxCalculateⅆⅆxyxwith change of variablesⅆⅆxyx=ⅆⅆθyθⅆⅆxθxCompute1stderivativeⅆⅆxyxⅆⅆxyx=ⅆⅆθyθx2+1Calculateⅆ2ⅆx2yxwith change of variablesⅆ2ⅆx2yx=ⅆ2ⅆθ2yθⅆⅆxθx2+ⅆ2ⅆx2θxⅆⅆθyθCompute2ndderivativeⅆ2ⅆx2yxⅆ2ⅆx2yx=ⅆ2ⅆθ2yθx2+1xⅆⅆθyθx2+132Apply the change of variables to the ODEx2+1ⅆ2ⅆθ2yθx2+1xⅆⅆθyθx2+132+xⅆⅆθyθx2+1+yx=0Multiply throughⅆ2ⅆθ2yθx2x2+1+ⅆ2ⅆθ2yθx2+1+x3ⅆⅆθyθx2+132xⅆⅆθyθx2+132+xⅆⅆθyθx2+1+yx=0Simplify ODEⅆ2ⅆθ2yθ+yx=0ODE is that of a harmonic oscillator with given general solutionyθ=C1sinθ+C2cosθRevert back toxyx=C1sinarccosx+C2cosarccosxUse trig identity to simplifysinarccosxsinarccosx=x2+1Simplify solution to the ODEyx=C1x2+1+C2xCheck validity of solutionyx=c__1x2+1+c__2xUse initial conditiony2=11=c__1−3+2c__2Compute derivative of the solutionⅆⅆxyx=c__1xx2+1+c__2Use the initial conditionⅆⅆxyxx=2|ⅆⅆxyxx=2=−1−1=2c__1−33+c__2Solve forc__1andc__2c__1=3−3,c__2=5Substitute constant values into general solution and simplifyyx=3I3x2+1+5xSolution to the IVPyx=3I3x2+1+5x

(10)

See Also

diff

Int

Student

Student[ODEs]

Student[ODEs][ODESteps]

 


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