Hi,
This is a bug for the monotonic decreasing data. You can try the xindex function to see whether it can work fine for your need. Such as:
// the second parameter is Col(2), but not Col(1) here
double nIdx1 = xindex(11781.20, Col(2)); type -a $(nIdx1); // Returns -1
double nIdx1 = xindex(11781.00, Col(2), 1); type -a $(nIdx1); // Returns -1
double nIdx1 = xindex(11781.00, Col(2), 2); type -a $(nIdx1); // Returns -1
Penn