All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
of 5

Please download to get full document.

View again

  On MATLAB command: dsolve   The MATLAB command dsolve computes symbolic solutions to ordinary differentialequations. Syntax dsolve('eq1','eq2',...,'cond1','cond2',...,'v') Description dsolve('eq1','eq2',...,'cond1','cond2',...,'v') symbolically solves the ordinary differential equationseq1, eq2,... using v as the independent variable. Here cond1,cond2,... specify boundary or initialconditions or both. You also can use the following syntax:dsolve('eq1, eq2',...,'cond1,cond2',...,'v').The default independent variable is t.The letter D denotes differentiation with respect to the independent variable. The primary defaultis d/dx. The letter D followed by a digit denotes repeated differentiation. For example, D2 isd  2 /dx 2 . Any character immediately following a differentiation operator is a dependent variable.For example, D3y denotes the third derivative of y(x) or y(t).You can specify initial and boundary conditions by equations like y(a) = b or Dy(a) = b, where yis a dependent variable and a and b are constants. If the number of the specified initial conditionsis less than the number of dependent variables, the resulting solutions contain the arbitraryconstants C1, C2,....You can input each equation or a condition as a separate symbolic equation.The dsolve command accepts up to 12 input arguments.dsolve can produce the following three types of outputs:For one equation and one output, dsolve returns the resulting solution with multiple solutionsto a nonlinear equation in a symbolic vector.For several equations and an equal number of outputs, dsolve sorts the results alphabeticallyand assigns them to the outputs.For several equations and a single output, dsolve returns a structure containing the solutions.If dsolve cannot find a closed-form (explicit) solution, it attempts to find an implicit solution.When dsolve returns an implicit solution, it issues a warning. If dsolve cannot find either anexplicit or an implicit solution, then it issues a warning and returns the empty sym. In such a case,  you can find a numeric solution, using the MATLAB ode45 functions (we will learn how to use it later). In some cases involving nonlinear equations, the output is an equivalent lower order differential equation or an integral. Example 1 : Solve 2* dy y t dt  = +   Solution:>> dsolve('Dy=2*y+t',’t’)ans =(C7*exp(2*t))/4 - t/2 - 1/4Or>> dsolve('Dy=2*y+t')ans =(C7*exp(2*t))/4 - t/2 - 1/4Remark: the default independent variable is t, if you do not specify in the command. Example 2 : Solve 2* , (0) 1 dy y t ydt  = + =   Solution:>> dsolve('Dy=2*y+t','y(0)=1','t')ans =(5*exp(2*t))/4 - t/2 - 1/4  Example 3 : Solve 2 2* , (0) 1 dy y x ydx = + =  >> dsolve('Dy=2*y+x^2','y(0)=1','x')ans =(5*exp(2*x))/4 - x/2 - x^2/2 - 1/4 Example 4 : Solve 22 2 , (0) 1, '(0) 0  x d y dye y ydx dx + = = =  Solution:>> dsolve('D2y+2*Dy=exp(x)','y(0)=1','Dy(0)=0','x')ans =1/(6*exp(2*x)) + exp(x)/3 + 1/2 Example 5 : Solve 22 2 sin( ), (0) 1, '(0) 1 d y dy x y ydx dx + = = − =  Solution:>> dsolve('D2y+2*Dy=sin(x)','y(0)=-1','Dy(0)=1','x')ans =- 3/(5*exp(2*x)) - (2*cos(x))/5 - sin(x)/5  How to plot   the solution of differential equation after you obtain the solution to thedifferential equation? Use ezplot See the following example. Example 5 : Solve 22 2 sin( ), (0) 1, '(0) 0 d y dy x y ydx dx + = = =   and plot the solution curve.Solution:>> sol=dsolve('D2y+2*Dy=exp(x)','y(0)=1','Dy(0)=0','x')sol =1/(6*exp(2*x)) + exp(x)/3 + 1/2>> ezplot(sol,[-2,4])>> -2-1012340246810121416x1/(6 exp(2 x)) + exp(x)/3 + 1/2
Similar documents
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks
Înregistrare | 1910 24 Vieh und Schlachthof Dresden Berlin Bebauung Tempelhofer Feld | Action Heroine Cheer Fruits Episode 9