Does anyone have the code to solve Kolmogorov forward equation using function PDEPE? I shall appreciate it very much. James ...

I have a system of equations contains one one-dimensional pde and three ode. Can it be solved by the 'pdepe' solver? If it can,how do I treat the boundary function of odes? ...

hello everyone i this error: ??? Error using ==> daeic12 at 77 This DAE appears to be of index greater than 1. Error in ==> ode15s at 395 [y,yp,f0,dfdy,nFE,nPD,Jfac] = daeic12(odeFcn,odeArgs,t,ICtype,Mt,y,yp0,f0,... Error in ==> pdepe at 320 [t,y] = ode15s(@pdeodes,t,y0,opts); Error in ==> ec_connu at 9 sol = pdepe(m,@pdex1pde,@pdex1ic,@pdex1bc,x,t); in this code: function ec_connu %con matlab N=100; m = 1; x = linspace(1e-300,2.5,100); t = linspace(0,1,N); sol = pdepe(m,@pdex1pde,@pdex1ic,@pdex1bc,x,t); % Extract the first solution component as u. u = sol(:,:,1); %...

Can pdepe solve the wave equation: 2 2 d u 2 d u ------ = v ------ 2 2 d t d x ...

Dear all, I am trying to solve a system of three coupled (nonlinear) differential equations containing first order derivatives in time and space, e.g. x-direction. When I try to solve the system I get the following error: "This DAE appears to be of index greater than 1." Maybe I am not allowed to set the second order derivatives to zero, because it is then neither parabolic nor elliptic. Boundary conditions are all set to zero. Did anybody encounter this same problem before? Thanks David Source code: function SRS_pde_solver_pulsed lambda_p=1.545e-6; % [m] g_R=10.5e-11; % Stim...

Hi everyone. First of all I'm sorry for the english. OK here is my problem. I'm trying to solve this equation [URL=http://img215.imageshack.us/i/im1c.png/][IMG]http://img215.imageshack.us/img215/8672/im1c.png[/IMG][/URL] The code for that (with some conditions) is here (go to the end to see my questions :-) ): function ec_connu_general3 N=100; m = 1; x = linspace(1,200,N); t = linspace(1,150,N); sol = pdepe(m,@pdex1pde,@pdex1ic,@pdex1bc,x,t); % Extract the first solution component as u. u = sol(:,:,1); save pro5.mat % A surface plot is often a good way to study a solution...

Problem - There is a cylinder filled with some spherical shaped filler particles with porosity 0.7. Some fluid at 673k is passed through it to charge it with heat energy. The governing equations are simultaneous PDEs. I want to solve ( to obtain the plots of u1 vs time and distance and u2 vs time and distance) this system of Partial differential equations using pdepe solver (or by any means). I got help from example no. 2 on this page ( http://www.mathworks.in/help/matlab/ref/pdepe.html ). Equations are:- (below d means partial differentiator and one can assume the vaue of constants) a1*(d...

Hello, I want to find zeros of a system of equations, eq=[eq(1),..,eq(n)]. But solve(eq) doesn't seem to work here, yet solve(eq(1),..,eq(n)) does. Suggestions? Thanks. ...

:For given example regarding usage of 'pdepe', multiple system of equations are defined at interval 0 to 1. My question is what if both equations are for different intervals say :0 to 5 : :5 to 8. and :Hence over all heat is transfered from 0 to 8. : BC are one bc at x=0 two BC at x=5 one BC at x=8 in all we have 4 BC and One IC for given set of 2 PDE. It would be of help if someone could help me out for solving this form of PDE. regards Jaidev Hello Jaidev, I know this post is really old, but did you get an answer to your problem? I...

i am new in matlab. Can any one help out in how to solve a the wave equation using finite difference methods(Say the five point method). I will be grateful. Thanks On May 13, 3:42=A0pm, "Kayanja Andy" <kayanja.and...@yahoo.com> wrote: > i am new in matlab. Can any one help out in how to solve a the wave equat= ion using finite difference methods(Say the five point method). I will be g= rateful. Thanks what have YOU done so far to solve YOUR particular problem... us "Kayanja Andy" <kayanja.andrew@yahoo.com> wrote in message news:hsgvjc$c11$1@f...

An iterative equation for solving the equation x^2-x-1=0 is given by x(r+1)=1+(1/x(r)) for r=0,1,2,... Given x0=2, write a Matlab script to solve the equation. Sufficient accuracy is obtained when abs(x(r+1)-x(r))<.0005. I am a new to Matlab and I am having a hard time really even starting this problem. I was thinking that using some sort of loop until the accuracy condition is met would work. Any help would be much appreciated. Thanks in advance, Jacob "Jacob" wrote in message <kdf58n$958$1@newscl01ah.mathworks.com>... > An iterative equation for solvin...

I compute a derivative of a function od fime which contains the variables ax,ay,bx,by,cx,cy,centerOfMassx,centerOfMassy, beta and v. These variables are all real numbers. By doing afgeleide = FullSimplify[ D[Cones[beta, v], v], {{ax, ay, bx, by, cx, cy, dx, dy, centerOfMassx, centerOfMassy} \[Element] Reals}, TimeConstraint -> 5] I get the following, for which I want to compute solutions = Solve[afgeleide == 0, v] But the problem is that this is too hard for my pc to solve with mathematica, can anyone help me to change the function so that mathematica can handle i...

I am trying to solve something like this: t = sym('t'); T = [t t t]'; v = (C-T)./delta; s = solve(v'*A^-1*(A^-1)'*v==1,t); C is 3x1, delta is 3x1, A is 3x3. I have some problems: 1) The solve-function takes too much time. I need to solve this problem for several different values of C, A and delta, as fast as possible. Is there a faster way of solving this problem? 2) I get some warning messages, such as: Warning: Explicit solution could not be found. > In solve at 179 In fmmComb>computeTau at 78 In fmmComb...

Hi all, Can you solve the following in matlab 2009b 64 bit (macosx with snow leopard)? I get the errors given below the code. It takes a lot of time before Matlab gives the error. Where do I go wrong? %----------------------- syms p0 p00 p1 p2 cn cr dn dr a an ar bn br T tau real; myfun = [ -(tau*(2*an + 2*bn*cn - 4*bn*p1 - dn*tau))/2; -(tau*(2*ar + 2*br*cr - 4*br*p0 - dr*tau))/2; ((T - tau)*(T*dn - 2*an - 2*bn*cn + 4*bn*p2 + dn*tau))/2; ((T - tau)*(T*dr - 2*ar - 2*br*cr + 4*br*p00 + dr*tau))/2; an*p2 - an*p1 - ar*p0 + ar*p00 + bn*p1^2 - bn*p2^2 + br*p0^2 - br*p00^2 - bn*cn*p1 + bn*c...

Hellow! I try to solve the following complex number equations: ..57656275472770359600926119844372e42*yita^2+.5438966091202114236344849 5468593e42*X^4-.22956779921876079684793874565208e42*X^6+.1690034374115 9551672322834315704e42+.54184776066768190965940275064713e41*i*X^5+.836 85682606372611137087763995977e41*i*X-.51266530898805208528073011534041 e41*i*X^3=0. so I use syms a x a=.57656275472770359600926119844372e42*yita^2+.54389660912021142363448 495468593e42*X^4-.22956779921876079684793874565208e42*X^6+.16900343741 159551672322834315704e42+.54184776066768190965940275064713e41*i*X^5+.8 3685682...

Hi all, I have an equation that gets executing many thousands of times by an algorithm. When I it is written in code the algorithm is quite fast. However, I want the user to be able to define the equation themselves, to solve it this way I use java expression parser (JEP). For a test example, the algorithm using the hard coded version runs in about 2 seconds, but using JEP, it takes in the order of 50 seconds! The expression is only parsed once by JEP, but evaluated many times with different values. The expression I'm using looks like: A - (B / C) * D Does anyone know if such a t...

Hi, I'm trzing to solve system of non-linear equations using "solve" and I gat this error message. Thak you for any help. --- code: syms x1 x2 x3 a1 a2 R50 R51 R16 R14 R35 R17 R19 R6 R52 R36 Fs =[a1*sin(x2)-R16*sin(x1)-R50, R16*cos(x1)+a1*cos(x2)-R51, R14^2-R51^2-R50^2, R16*cos(x1)+(a1+a2)*cos(x2)+R35*cos(x3)-R52, (a1+a2)*sin(x2)-R16*sin(x1)-R35*sin(x3)-(R19-R6)/2, x1+x2-R17, x2+x3-R36]; [x1,x2,x3,a1,a2,R50,R51]=solve(Fs); --- message: "Error, (in solve) invalid arguments" P.S.: I tried solving it using "fsolve" but there I get this message (Optimizatio...

Hello I am using the solve command as follow [u,v] = solve('a*u^2 + v^2 = 0','u - v = 1') my problem is that even if I define or tell matlab what "a" is, it solve the 2 equations treating "a" as an unknown parameters. I can always use the "subs" command after the solve command to subsitute "a" by its value. However, it is not an option for what I want to do. I want to automate the solve process, so hard coding the value of "a" in the equations is not options i.e let say a=2 [u,v] = solve('2*u^2 + v^2 = 0','u - v =...

How can I simulate or solve this kind of difference equation? x(k+2)-7x(k+1)+12x(k)=0 A for loop would work nicely. This particular system is unstable. -James Tama Tomi wrote: > How can I simulate or solve this kind of difference equation? > > x(k+2)-7x(k+1)+12x(k)=0 Can you give me a example? James Allison <james.allison@mathworks.com> wrote in message <hmr9fp$62s$1@fred.mathworks.com>... > A for loop would work nicely. This particular system is unstable. > > -James > > Tama Tomi wrote: > > How can I simulate or solve this kind of...

I am trying to solve something like this: t = sym('t'); T = [t t t]'; v = (C-T)./delta; s = solve(v'*A^-1*(A^-1)'*v==1,t); C is 3x1, delta is 3x1, A is 3x3. I have some problems: 1) The solve-function takes too much time. I need to solve this problem for several different values of C, A and delta, as fast as possible. Is there a faster way of solving this problem? 2) I get some warning messages, such as: Warning: Explicit solution could not be found. > In solve at 179 In fmmComb>computeTau at 78 In fmmComb...

Hi All, Given that the following equation is true. Clear[NoOf360Rotations] NoOf360Rotations = 108 ArcTan[Tan[Degree*(180 - 1.5267134447254718*(18.43494882292201 + 360*NoOf360Rotations))]] == 0.23101849674392247 TRUE How can I solve this equation with Solve or Reduce or whatever for the required value NoOf360Rotations = 108 Only want Integer return of NoOf360Rotations AND to equal 108 Any help or advice gratefully received. Best regards, Lea=85 ...

Hello everyone, Today I met a problem when I was trying to solve the Differential- Algebraic equations. what can cause this warning: 1, "Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN." 2, Warning: Failure at t=0.000000e+000. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (7.905050e-323) at time t. The code is as follows: clear clc %% constant prarameters nm = 10^-9; ms = 10^-3; c=2.998*10^8; um=10^-6; Epsilon_0=8.85*10^-12; neff=1.45; ...

> ArcTan[Tan[Degree*(180 - 1.5267134447254718*(18.43494882292201 + > 360*NoOf360Rotations))]] == 0.23101849674392247 > Only want Integer return of NoOf360Rotations AND to equal 108 Hi. Another way might be to move everything to the left-hand side of the equation. ArcTan[Tan[Degree*(180-1.5267134447254718*(18.43494882292201+360*x))]] - 0.23101849674392247 f=FullSimplify[%] -0.231018+ArcTan[Tan[2.65037 -9.59262 x]] Now: Minimize[{Abs[f],0<x<200},x,Integers] {2.77556*10^-17,{x->108}} The value of 2.77*10^-17 is pretty close to zero, and will t...

Hi all, I am trying to find solution of the two interdependent trigonometric transcendental equations with solve command. The equations can be solved by the MATLAB command "solve" but the solution i get from the solve command for two variables is in "atan" form and not in a form of value. can anyone please guide me how to get the solution set as a numbers and not in form of long equation forms. Also sending the code of MATLAB. syms thx thz disp ('enter the distance of travel'); D = input ('enter distance in mm : '); disp ('enter the f...

Hello all, I working with the nonlinear solver lsqnonlin in order to solve a nonlinear equation system f(x)-g(x) = 0. There two different types of equations in this system, ie. f1(x)-g1(x) and f2(x)-g2(x). The absolute values of the f and g are very different for these two types. The first ist about 1 and the other in the range of 1*10-6. This means that although I have quite good starting values, the values of the two equations f1(x0)-g1(x0) and f2(x0)-g2(x0) are extremly differing by many orders of magnitude. Because of that, lsqnonlin is only optimizing the first equations with the larger ...