# NAG C Library - Decision Trees

## Selecting the best routine

Decision Trees within many Chapter Introductions in the NAG C Library Manual make finding the right routine easier and quicker than ever before.

The trees lead the user through some simple yes/no questions that categorize the problem and lead to suggestions of the most suitable functions to be used.

The following links will bring you to the location of the decision trees in the chapters indicated for the NAG C Library Mark 25 documentation.

Chapter Title Tree Descriptions Chapter & Links
Roots of One or More Transcendental Equations Tree 1: Functions of One Variable
Tree 2: Functions of several variables
Chapter c05
Decision trees
Quadrature Tree 1: One-dimensional integrals over a finite interval
Tree 2: One-dimensional integrals over a semi-infinite or infinite interval
Tree 3: Multidimensional integrals
Chapter d01
Decision trees
Ordinary Differential Equations Tree 1: Initial Value Problems
Tree 2: Boundary Value Problems
Chapter d02
Decision trees
Partial Differential Equations Tree 1: PDEs
Tree 2: Hyperbolic branch
Tree 3: Parabolic branch
Tree 4: Branch for parabolic PDE in non-conservative form
Chapter d03
Decision trees
Interpolation Tree 1: Interpolation Chapter e01
Decision trees
Curve and Surface Fitting Tree 1: Unconstrained fitting
Tree 2: Unconstrained fitting
Chapter e02
Decision trees
Minimizing or Maximizing a Function Tree 1: Selection chart for unconstrained problems
Tree 2: Selection chart for bound-constrained, linearly-constrained and nonlinearly-constrained problems
Tree 3: Linear programming
Chapter e04
Decision trees
Matrix Operations, Including Inversion Tree 1: Matrix Inversion
Tree 2: Inverse of a real n by n matrix of full rank
Tree 3: Inverse of a complex n by n matrix of full rank
Tree 4: Pseudo-inverses
Chapter f01
Decision trees
Eigenvalues and Eigenvectors Tree 1: Eigenvalues and Eigenvectors of Real Matrices
Tree 2: Eigenvalues and Eigenvectors of Complex Matrices
Tree 3: Singular Values and Singular Vectors
Chapter f02
Decision trees
Determinants Tree 1: Determinants Chapter f03
Decision trees
Simultaneous Linear Equations Tree 1: Black Box functions for unique solution of A x = b (Real matrix)
Tree 2: Black Box functions for unique solution of A x = b (Complex matrix)
Tree 3: General purpose functions for unique solution of A x = b (Real matrix)
Tree 4: General purpose functions for unique solution of A x = b (Complex matrix)
Chapter f04
Decision trees
Least Squares and Eigenvalue Problems (LAPACK) Tree 1: Real Symmetric Eigenvalue Problems
Tree 2: Real Generalized Symmetric-definite Eigenvalue Problems
Tree 3: Real Nonsymmetric Eigenvalue Problems
Tree 4: Real Generalized Nonsymmetric Eigenvalue Problems
Tree 5: Complex Hermitian Eigenvalue Problems
Tree 6: Complex Generalized Hermitian-definite Eigenvalue Problems
Tree 7: Complex non-Hermitian Eigenvalue Problems
Tree 8: Complex Generalized non-Hermitian Eigenvalue Problems
Chapter f08
Decision trees
Large Scale Linear Systems Tree 1: Solvers Chapter f11
Decision trees