I HAVE THE FOLLOWING ERROR: "Error using bvparguments" HELP ME TO FIX IT

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REVATHI DEVI 2022-12-30

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编辑： Torsten 2023-1-3

采纳的回答： Jan

Error using bvparguments (line 108)

Error in calling BVP4C(ODEFUN,BCFUN,SOLINIT):

The derivative function ODEFUN should return a column vector of length 8.

Error in bvp4c (line 122)

bvparguments(solver_name,ode,bc,solinit,options,varargin);

Error in second (line 25)

sol =bvp4c(@shootode,@shootbc,solinit);

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REVATHI DEVI 2023-1-3

no sir this is the example which is in matlab tutorials

function mmbvp

%MMBVP Exercise for Example 7 of the BVP tutorial.

% This is the Michaelis-Menten kinetics problem solved in section 6.2 of

% H.B. Keller, Numerical Methods for Two-Point Boundary-Value Problems,

% Dover, New York, 1992, for parameters epsilon = 0.1 and k = 0.1.

% Known parameters

epsilon = 0.1;

k = 0.1;

d = 0.001;

options = bvpset('stats','on');

solinit = bvpinit(linspace(d,1,5),[0.01 0],0.01);

sol = bvp4c(@mmode,@mmbc,solinit,options,epsilon,k,d);

p = sol.parameters; % unknown parameter

xint = linspace(d,1);

Sxint = bvpval(sol,xint);

% Augment the solution array with the values y(0) = p, y'(0) = 0

% to get a solution on [0, 1]. For this problem the solution is

% flat near x = 0, but if it had been necessary for a smooth graph,

% other values in [0,d] could have been obtained from the series.

x = [0 xint];

y = [[p; 0] Sxint];

clf reset

plot(x,y(1,:))

title('Michaelis-Menten kinetics problem with coordinate singularity.')

shg

% --------------------------------------------------------------------------

function dydx = mmode(x,y,p,epsilon,k,d)

%MMODE ODE function for the exercise of Example 7 of the BVP tutorial.

% On the argument list the known parameters must follow the unknown one.

dydx = [ y(2)

-2*(y(2)/x) + y(1)/(epsilon*(y(1) + k)) ];

% --------------------------------------------------------------------------

function res = mmbc(ya,yb,p,epsilon,k,d)

%MMBC Boundary conditions for the exercise of Example 7 of the BVP tutorial.

% On the argument list the known parameters must follow the unknown one.

% The boundary conditions at x = d are that y and y' have values yatd and

% ypatd obtained from series expansions. The unknown parameter p = y(0)

% is used in the expansions. y''(d) also appears in the expansions.

% It is evaluated as a limit in the differential equation.

yp2atd = p /(3*epsilon*(p + k));

yatd = p + 0.5*yp2atd*d^2;

ypatd = yp2atd*d;

res = [ yb(1) - 1

ya(1) - yatd

ya(2) - ypatd ];

REVATHI DEVI 2023-1-3

yes sir are you there sir

my question is i have 7 derivative functions and 8 boundary conditions

Torsten 2023-1-3

编辑：Torsten 2023-1-3

In the code you posted above, there is a third free parameter p that is to be adjusted so that all three instead of only two boundary conditions can be satisfied. Your original problem - which you deleted for some resason - did not contain such a free parameter.

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Answer 1

Jan 2022-12-30

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移动：Jan 2022-12-30

The code does not run.

linspace(0,infinity,40) - what is "infinity" and of course you cannot divide the interval [0, Infinity] into 40 steps.
The functions need trailing end statements if this is written in a single file.
You provide an initial value with 8 components, but as the error message tells clearly, shootode replies 7 elements only.

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REVATHI DEVI 2022-12-31

for infinity value is consider as 6 and i have 7equations and 8 boundaries that is my problem

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Answer 2

Walter Roberson 2022-12-31

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you do not initialize your global variables, so some of your calculations return empty

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REVATHI DEVI 2022-12-31

i have initialized

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I HAVE THE FOLLOWING ERROR: "Error using bvparguments" HELP ME TO FIX IT

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I HAVE THE FOLLOWING ERROR: "Error using bvparguments" HELP ME TO FIX IT

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