An equation derived from observation and/or condition equations by including undetermined multipliers (Lagrangian multipliers) and expressing the condition that the sum of the squares of the residuals (or corrections) resulting from the application of these multipliers to the condition equations shall be a minimum. In adjusting triangulation by the method of least squares, correlate equations are formed directly from the observation and condition equations, there being as many correlate equations as there are corrections to be determined, but only as many undetermined multipliers as there are condition equations. From these correlate equations, new equations are formed equal in number to the number of undetermined multipliers which constitute the unknowns. Solving these equations determines values for the multipliers which, when substituted into the correlate equations, give values for the corrections which satisfy the condition equations, make the measurements and their functions consistent among themselves, and make the adjusted values the most probable that can be derived from the given measurements.