Error when building a trend line

  [cat,nocat]=min(Animals);  % cat and dog 1x1200
  [dog,nodog=max(Animals);  % cat and dog 1x1200
  for i=1:length(cat)
  pas(i) = polyfit(cat(i),dog(i),1);  % error Subscripted assignment dimension mismatch.
  fss(i) = polyval(dog(i),cat(i)); 
  end

I'm trying to build a trend line of two values ​​of cats and dogs, but I get an error, help me figure out what's wrong.

Probyval without a loop, gives only the latest values.

Answer 1

[Shashank Sharma]

polyfit requires x , y to be vectors. Also, it makes no sense to fit a single value.

It seems to me that your usage of polyval is wrong. Take a look at the docs

https://www.mathworks.com/help/matlab/ref/polyval.html

This is probably what you should be doing,

pas = polyfit(cat,dog,1);
dog_fit = polyval(pas, cat);