相互检查两个向量的值，然后使用相等条目的列位置从Matlab中的矩阵中提取列

Question

I'm doing a curve fitting problem in Matlab and so far I've set up some orthonormal polynomials along a specified range of x-values with x = (0:0.0001:40);

The polynomials themselves are each a manipulation of that x vector and are stored as a row in a matrix. I also have some have data entries in the form of two vectors - one for the data x-coords and one for the actual values. I need a way to use the x-coords of my data points to find the same values in my continuous x-vector and then take the corresponding columns from my polynomial matrix and add them to a new matrix.

EDIT: To be more clear. I have, for example:

x = [0 1 2 3 4 5]
Polynomial =

      1     1     1     1     1     1
      0     1     2     3     4     5
      0     1     4     9     16    25

% Data values:
x-coord = [1 3 4]
values = [5 3 8]

I want to check the x-coord values against 'x' to find the corresponding columns and then pull out those columns from the polynomial matrix to get:

Polynomial =

          1     1     1
          1     3     4
          1     9     16

Answer 1

If your x , Polynomial , and xcoord are the same length you could use logical indexing which is elegant; something along the lines of Polynomial(x==xcoord) . But since this doesn't seem to be the case, there's a less fancy solution with a for-loop and find(xcoord(i)==x)