*4.2.1 SOLVER® iteration and optimization tool*

To use SOLVER®, a model of the decision problem that specifies the following is built; (i) the measure to optimize, called the objective (ii) the decisions to be

*Perspective Chapter: Rheological Considerations for Drilling and Enhanced Oil Recovery… DOI: http://dx.doi.org/10.5772/intechopen.106897*


made, called decision variables (iii) any logical restrictions on potential solutions, called constraints. It would find values for the decision variables (τy, n, and k) that satisfy the constraints while optimizing (maximizing or minimizing) the objective (**Figure 3**). It changes the decision variables (iteration) as many times as possible to make the squared sum (SS) error between the data and the fit as small as possible. It does that with all the data points, trying to minimize them (constraints) while trying to make the SS error as small as possible using the generalized reduced gradient technique. The constraint precision and generalized reduced gradient convergence could be adjusted using the options tab.
