Subscript indices must be real positive error

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I am trying to run a code(part of which is mentioned below) where h,u and x values have been defined separately in the rest of the code.. When I try to run this code to plot piecewise function, it gives me the following error "Subscript indices must either be real positive integers or logicals.

Error in fem51uapprox (line 78) y(c:d-1)=r.^2; %u(2*m-1,1).*w1+u(2*m,1).*w2+u(2*m+1,1).*w3;"

Can anybody please tell me what I am supposed to do to get rid of the error?

r=0:0.01:1;

y=zeros(length(x));

for m=1:n

    w1=(1./h).*(r-x(2.*m)).*((2./h).*(r-x(2.*m))-1);
    w2=(1-(2./h).*(r-x(2.*m))).*((2./h).*(r-x(2.*m))+1);
    w3=(1./h).*(r-x(2.*m)).*((2./h).*(r-x(2.*m))+1);
    c=round((m-1)*h*100);
    d=round(m*h*100);
    y(c:d-1)=r.^2; %u(2*m-1,1).*w1+u(2*m,1).*w2+u(2*m+1,1).*w3;
end

a=0:0.001:1;

b=(1-((1+a).^(3./2)))./3;

plot(r,y,a,b,'b');