How to create square symetric criterion matrix for random numbers of points

Hi! I have a problem creating matrix of 2D geodetic network.

I would really appreciate if someone knows how to make it!

Matrix should have such form:

- Number of points and cooridnates of points are random!

- On the main diagonal of a square and symmetric matrix there are only numbers 1 (where lies x1, x2, ...xn,yn)!! - this are like variances

- On the other places i have to compute distance between any number of points (d12, d13,...d1n) - this are like covariances

 C  = [x1     0      d12    0     d13   0      d14    0   ...    d1n   0;

       0      y1     0     d12   0     d13    0      d14  ...    0     d1n;

       d12    0      x2    0     d23   0      d24    0    ...    d2n   0;

       0      d12    0     y2    0     d23    0      d24  ...    0     d2n;

       d13    0      d23   0     x3    0      d34    0    ...    d3n   0;

       0      d13    0     d23   0     y3     0      d34  ...    0     d3n;

      d14    0      d24   0     d34    0     x4     0    ...    d4n   0;

       0      d14    0     d24   0     d34    0      y4   ...    0     d4n;

       .      .      .    .      .      .      .    .     ...    .     .

       .      .      .    .      .      .      .    .     ...    .     .

       .      .      .    .      .      .      .    .     ...    .     .

       dn1    0      dn2   0     dn3    0     dn4    0    ...     xn   0;

       0      dn1    0     dn2   0     dn3    0      dn4   ...    0   yn];

Thank you,

bye!