Not enough input arguments. Error in odefun (line 2) y1 = y(1); Error in bvp4c (line 5) sol =bvp4c(ode​fun,bcfun,​solinit);

function dydx = odefun(y,x) % equation to solve
y1 = y(1);
y2= y(2);
dy1_dx = y(2);
dy2_dx = [U*y2+K*y1/D];
dy_dx = [dy_dx; dy2_dx];
end
function bcfun=bvp_bc(ya,yb)
bc=[ya(1)-3*yb(1)-2];
guess =[2;1];
xmesh = linspace(0,1,5);
solinit = bvpinit(xmesh,guess);

sol =bvp4c(odefun,bcfun,solinit);

plot(sol.x,sol.y(1,:),'--o');
title('chlorine decay')
xlabel('pipe length(m)');
ylabel('Concentration (mg/L)');
function dydx = ode(x,y)
D=0.1; % m2/s
U=1; % m/s
K = 1*10^-6; % 1/s
dydx = [y(2)*(U*y(2)+K*y(1))/D];
end
function res = bc(ya,yb)
res = [ya(1)-3 yb(1)-2];
end

I need to plot C vs x using Matlab's BVP4C

Answer 1

[Walter Roberson]

As we told you in one of your other questions, the first two parameters to bvp4c need to be function handles, not function names. As in bvp4c(@odefun, @bcfun, solinit)

[Naveen Krish]

Execution of script bvp4c as a function is not supported:

Error in bvp4c (line 5)

sol =bvp4c(@odefun,@bcfun,solinit);

[Torsten]

@Naveen Krish

Did you manage to make one of MATLAB's example codes work ?

[Naveen Krish]

Which example?

[Torsten]

Did you never use MATLAB examples ?

Type

help bvp4c

Or load the examples directly from the website:

https://de.mathworks.com/help/matlab/ref/bvp4c.html

[Naveen Krish]

I did my code by those examples only. But still couldn't figure out where it went wrong

[Torsten]

So, this is the first example from the MATLAB website:

xmesh = linspace(0,pi/2,5);
solinit = bvpinit(xmesh, @guess);
sol = bvp4c(@bvpfcn, @bcfcn, solinit);
plot(sol.x, sol.y, '-o')

function dydx = bvpfcn(x,y)
dydx = zeros(2,1);
dydx = [y(2)
       -y(1)];
end
function res = bcfcn(ya,yb)
res = [ya(1)
       yb(1)-2];
end
function g = guess(x)
g = [sin(x)
    cos(x)];
end

Does it work on your PC ?

[Walter Roberson]

Execution of script bvp4c as a function is not supported:

Error in bvp4c (line 5)

You named your own code bvp4c which is exactly what we have been saying you must not do.

You need to rename your bvp4c.m to something else like find_bv.m

I asked you repeatedly to show us the output of

which -all bvp4c

but you never did. If you had shown us that output when we first asked for it, the problem would have been solved many hours ago.

[Naveen Krish]

Where should i use this command

which -all bvp4c ?

[Naveen Krish]

Error: File: bp4.m Line: 21 Column: 1

The function "bc" was closed with an 'end', but at least one other function definition was not. To avoid confusion when using

nested functions, it is illegal to use both conventions in the same file.

function dydx = odefun(y,x) % equation to solve
y1 = y(1);
y2= y(2);
dy1_dx = y(2);
dy2_dx = [U*y2+K*y1/D];
dy_dx = [dy_dx; dy2_dx];
end
function bcfun=bvp_bc(ya,yb)
bc=[ya(1)-3*yb(1)-2];
guess =[2;1];
xmesh = linspace(0,1,5);
solinit = bvpinit(xmesh,guess);
sol =bvp4c(@odefun,@bcfun,solinit);
which -all bvp4c
plot(sol.x,sol.y(1,:),'--o');
title('chlorine decay')
xlabel('pipe length(m)');
ylabel('Concentration (mg/L)');
function dydx = ode(x,y)
D=0.1; % m2/s
U=1; % m/s
K = 1*10^-6; % 1/s
dydx = [y(2)*(U*y(2)+K*y(1))/D];
end
function res = bc(ya,yb)
res = [ya(1)-3 yb(1)-2];
end

[Walter Roberson]

guess =[2;1];
xmesh = linspace(0,1,5);
solinit = bvpinit(xmesh,guess);
sol = bvp4c(@odefun,@bcfun,solinit);
plot(sol.x,sol.y(1,:),'--o');
title('chlorine decay')
xlabel('pipe length(m)');
ylabel('Concentration (mg/L)');

function dydx = odefun(y,x) % equation to solve
    y1 = y(1);
    y2= y(2);
    dy1_dx = y(2);
    dy2_dx = [U*y2+K*y1/D];
    dy_dx = [dy_dx; dy2_dx];
end

function res = bcfun(ya,yb)
    res = [ya(1)-3
           yb(1)-2];
end

Answer 2

[MOSLI KARIM]

function ANSWER_MATHWORKII
D=0.1; % m2/s
U=1; % m/s
K = 1*10^-6;% equation to solve
guess =[2;1];


xmesh = linspace(0,1,5);

solinit = bvpinit(xmesh,guess);
sol =bvp4c(@fct,@bc,solinit);
plot(sol.x,sol.y(1,:),'--o');
title('chlorine decay')
xlabel('pipe length(m)');
ylabel('Concentration (mg/L)');



 
% dydx = [y(2) ; U*y(2)+(K*y(1))/D];
 
function yp=fct(x,y)
yp=[y(2);U*y(2)+(K*y(1))/D  ];    
 end 
 
function res = bc(ya,yb)
res = [ya(1)-3 ;yb(1)-2];
end

end