Having errors in a multivariable for loop.

I have this following code in order to find the values of vmax with varying h and x. The values are to be inputted into a single matrix. I am receiving the error message: Array indices must be positive integers or logical values.

function [vmax] = v1(temp_diff,h)
vmax=0.083*sqrt(temp_diff*h);
end
function [vmax] = v2(x,temp_diff,h)
vmax=[0.143/(x+1.32)]*sqrt(temp_diff*h);
end
function [vmax] = v3(temp_diff,h)
vmax=0.043*sqrt(temp_diff*h);
end

temp_int=24;
temp_ext=10;
U=5;
hi=4;
h=1:5;
temp_diff=(U/hi)*(temp_int-temp_ext);
x=0:0.1:2.5;
X=repmat(x,size(h,2),1);
H=repmat(x,size(x,2),2);
n=length(x);
m=length(h);
V=zeros(n,m);

for i=0:0.1:2.5
    for h=1:5
        if i<0.4
            vmax(i)=v1(temp_diff(i),h(i));
        elseif i<=2
            vmax(i)=v2(temp_diff(i),h(i),x(i));
        else
            vmax(i)=v3(temp_diff(i),h(i));
            
        end
    end
end

Hoping someone with more experience can help me out!

Answer 1

[VBBV]

temp_int=24;
temp_ext=10;
U=5;
hi=4;
h=1:5;
temp_diff=(U/hi)*(temp_int-temp_ext);


I = 0:0.1:2.5;
x = 0:0.1:2.5;

n=length(x);
m=length(h);
V=zeros(n,m);
X=repmat(x,size(h,2),1);
H=repmat(x,size(x,2),2);



for ii = 1:length(I)  % chnage the loop index // variable //from 0 to 1
    for h=1:5
        if I(ii)<0.4
            vmax(ii)=v1(temp_diff,h);
        elseif I(ii)<=2
            vmax(ii)=v2(temp_diff,h,x(ii));
        else
            vmax(ii)=v3(temp_diff,h);            
        end
    end
end
plot(I,vmax)

function [vmax] = v1(temp_diff,h)
vmax=0.083*sqrt(temp_diff*h);
end
function [vmax] = v2(x,temp_diff,h)
vmax=[0.143/(x+1.32)]*sqrt(temp_diff*h);
end
function [vmax] = v3(temp_diff,h)
vmax=0.043*sqrt(temp_diff*h);
end

Modfy the loop so that array indices are positive integers and not zeros

Answer 2

[Arif Hoq]

try this:

temp_int=24;
temp_ext=10;
U=5;
hi=4;
h=1:5;
temp_diff=(U/hi)*(temp_int-temp_ext);
x=0:0.1:2.5;
X=repmat(x,size(h,2),1);   % you are not using this parameter in your code
H=repmat(x,size(x,2),2);    % you are not using this parameter in your code
n=length(x);
m=length(h);
V=zeros(n,m);
for i=1:5               % for loop for value of h
    for j=1:length(x)   % for loop for value of x
        if i<0.4
            vmax(i)=v1(temp_diff,h(i));  % as temp_diff is a scalar so you don't need indexing
        elseif i<=2
            vmax(i)=v2(temp_diff,h(i),x(j));
        else
            vmax(i)=v3(temp_diff,h(i));            
        end
    end
end