Error using reshape Number of elements must not change. Use [] as one of the size inputs to automatically calculate the appropriate size for that dimension.

% dening data points, vectors x and y
x_value = [0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5];
y_value = [0 0.2474665 0.8813736 1.550158 2.0947125 2.5320681 2.893444 3.2003349 3.466711 3.7019111 3.9124228];
% dening x in range 0 to 5 with total 100 values
xx = linspace(0,5,100);
plot(x_value, y_value,'O')


%calculation of coeffiecients
for i=1:xx
    for j=1:xx
        c.c(i,j)=(x_value(1,i)-x_value(1,j));
    end
end
c=c.*c;
q=size(c);
c=c';
c(c==0)=[];%deleting the zero values from the matrix
c=reshape(c,q(2)-1,q(1));

c=reshape(c,q(2)-1,q(1)); -> Error in Project (line 19)

c=c';
j=1;
for i=1:xx
    d.d(i,j)=prod(c(i,:));
end
d=d.d;
d=d';
for i=1:xx
    coff.coff(i,j)=y_value(1,i)./d(1,i);
end
coff=coff.coff;
coff=coff';%coefficients

for i=1:xx
    for j=1:xx
        p.p(i,j)=(x-x_value(1,j));
    end
end
p=p.p;
m=size(p);
p=p';
p(1:xx+1:end)=[];%deleting the diagonal elements
p=reshape(p,m(2)-1,m(1));

p=prod(p);
pol=coff.*p;                            
pol=sum(pol);%Lagrange polynomial

l=input('Enter a value to compute the b value:');
output=subs(pol,l);

%Displaying output
disp('');
fprintf('Value of input x:=%f\n',double(output));

if l>max(x_value)
    x=min(x_value):0.1:l;
    y=subs(pol,x);
    plot(x,y,'r');
    xlabel('X')
    ylabel('Y')
else
    x=min(x_value):0.1:max(x_value);
    y=subs(pol,x);
    plot(x,y,'r');
    xlabel('X')
    ylabel('Y')
end

At line 19, the 'Error using reshape Number of elements must not change. Use [] as one of the size inputs to automatically calculate the appropriate size for that dimension. ' I am getting this error. How can I solve this problem. Thank you for your help.

Answer 1

[Image Analyst]

When you say this:

c.c(i,j)=(x_value(1,i)-x_value(1,j));

you're saying that you're assigning the right hand side to a field called "c" that is a member of a structure also (unfortunately) called "c". Why are you doing that?

Then you do this

c=c.*c;
q=size(c);
c=c';
c(c==0)=[];%deleting the zero values from the matrix
c=reshape(c,q(2)-1,q(1));

The first line will not even work since you can't square a structure. But anyway, you get q based on the size of c but then delete some elements from c so the size of c changes. However you never updated q. Why didn't you? And why do you want c to be a 2D array? What is the overall intent of this code? Some kind of filtering, convolution, or gradient?

The whole code is a mess and I think you'll discover the error if you do two things:

1. Use more descriptive variable names, not a collection of names that looks like alphabet soup.
2. Use a comment in front of every chunk of code to describe that that chunk of code actually does.

[the cyclist]

Agreed with all of the above. There many problems with this code. Did you write it, or copy it from somewhere? Are you trying to convert something from another coding language?

Here is another issue, not mentioned in ImageAnalyst's answer. You write a loop like this

for i = 1:xx

but xx is the vector

linspace(0,5,100)

so it is unclear to me what you intend to happen here, since the loop is

for i = 1:[0 0.0505 0.1010 .. and so on .. 4.9495 5]

and I believe this loop will be bypassed with nothing happening at all.

It also seems like you might have been intending the loop to fill in values such as

c(0.0505,0.0505)

which will also cause problems.

[Kutlu Yigitturk]

This is the question I have to solve. The code I wrote above is a quote from somewhere else, I tried to integrate that code I got into my code.

[Image Analyst]

For spline, you can use interp1() or spline(). See attached demo.