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

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Naveen Krish 2022-3-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1675184-not-enough-input-arguments-error-in-odefun-line-2-y1-y-1-error-in-bvp4c-line-5-sol-bvp4c

回答： MOSLI KARIM 2022-12-17

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

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回答（2 个）

Walter Roberson 2022-3-19

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1675184-not-enough-input-arguments-error-in-odefun-line-2-y1-y-1-error-in-bvp4c-line-5-sol-bvp4c#answer_921444

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)

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Naveen Krish 2022-3-19

编辑：Walter Roberson 2022-3-21

在 MATLAB Online 中打开

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 2022-3-21

在 MATLAB Online 中打开

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

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MOSLI KARIM 2022-12-17

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1675184-not-enough-input-arguments-error-in-odefun-line-2-y1-y-1-error-in-bvp4c-line-5-sol-bvp4c#answer_1130007

在 MATLAB Online 中打开

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 