How to take x as a vector in for loop?

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Qudsiya  Irum
Qudsiya Irum on 7 Sep 2017
Commented: Eric on 8 Sep 2017
NN=zeros(nx+1,nx+1);
xx=0.998;
for i=1:nx+1
count=1;
for x=dx:length: nx+1
if(i-1)*xx<=x<=i*xx
i;
NN(i,count)=(x-(i-1)*dx)/dx;
elseif i*xx<=x<=(i+1)*xx
i;
NN(i,count)=((i+1)*dx-x)/dx;
end
NN(NN<0)=0;
count=count+1;
end
end
This code shows dimension error in
T_check = interp1(xts,pts,x,'linear');
because x is showing only one value here. Anyone please guide me how to correct x?
  1 Comment
Stephen23
Stephen23 on 7 Sep 2017
@Qudsiya Irum: your code is very badly indented. Bad code alignment is a common way that beginners hide errors in their code. Fixing code indentation is easy: click ctrl+i in the MATLAB editor.

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Accepted Answer

Eric
Eric on 7 Sep 2017
The variable x here is a for loop counter, which means it will iterate through the values given by dx:length:nx+1 and therefore only ever have one value at a time. If you want x to be the entire vector, set x=dx:length:nx+1 again on its own after the for loop.
Protip: You can set x before the for loop as well and change the iterator to
for i=1:size(x)
or something of that nature. Then you can index into x using x(i) and still have x as a vector and only look at a single value in x.
Protip: Use ctrl-i for proper indenting, as Stephen described in his comment. It really does make reading code easier for both you and us on MATLAB Answers.
Protip: Do not use MATLAB functions as variable names (e.g. length, count). Choose names like xlength or counter, even if you are not using the MATLAB functions. This way you will not override the MATLAB function now or in the future and will avoid any headaches that that may cause.
  1 Comment
Stephen23
Stephen23 on 7 Sep 2017
"Use ctrl-i for proper indenting... It really does make reading code easier for both you and us on MATLAB Answers."
Code that is easier to read is easier to understand. Code that is easier to understand has fewer bugs. Code that has fewer bugs wastes less of your life debugging.
Summary: Indent your code consistently!

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More Answers (1)

Qudsiya  Irum
Qudsiya Irum on 8 Sep 2017
Edited: Stephen23 on 8 Sep 2017
Thanks for comments! Please see the code, is this correct in indent??
NN=zeros(nx+1,nx+1);
xx=0.998;
for i=1:nx+1
counter=1;
for x=dx:xlength: nx+1
if(i-1)*xx<=x<=i*xx
i;
NN(i,counter)=(x-(i-1)*dx)/dx;
elseif i*xx<=x<=(i+1)*xx
i;
NN(i,counter)=((i+1)*dx-x)/dx;
end
NN(NN<0)=0;
counert=counter+1;
end
end
I want to obtain a NN matrix of (2501*2501) with condition that for interval (i-1)*xx<=x<=i*xx, it should return value 1 otherwise 0 for whole iteration. But I am not getting x as a vector at the end.please guide me.
  2 Comments
Eric
Eric on 8 Sep 2017
"If you want x to be the entire vector, set x=dx:length:nx+1 again on its own after the for loop."
As I mentioned previously, the way to get x as a vector with minimal changes to your code is to add the line
x =dx:xlength:nx+1
to the end of your code.

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