How to find x for a given value of y?

I have found eigenvector h given matrix g. To do that, i have constructed a grid of random numbers : % generate grid

dx = (x_max-x_min)/(n_max-1); grid_x=linspace(x_min, x_max, n_max); grid_x = (grid_x(1:end-1)+grid_x(2:end))/2;

g = []; for i=1:n_max-1

    g = [g; dx*normpdf(grid_x, grid_x(i), sigma)];
end

% find eigenvalues [V, lambda] = eig(g);

h = V(:, end);

Now I'd like to know how to get the value on the grid 'x', which would correspond to the random draw of some number from the eigenvector h??

Thanks.