Numerical Parameters

The &num namelist group defines numerical method parameters; the input file can contain one or more, but only the last (tag-matching) one is used. Allowable fields are:

diff_scheme (default 'COLLOC_GL2')

Difference equation scheme; one of:

  • 'COLLOC_GL2' : Second-order Gauss-Legendre collocation

  • 'COLLOC_GL4' : Fourth-order Gauss-Legendre collocation

  • 'COLLOC_GL6' : Sixth-order Gauss-Legendre collocation

  • 'MAGNUS_GL2' : Second-order Gauss-Legendre Magnus

  • 'MAGNUS_GL4' : Fourth-order Gauss-Legendre Magnus

  • 'MAGNUS_GL6' : Sixth-order Gauss-Legendre Magnus

  • 'MIRK' : Fourth-order mono-implicit Runge-Kutta (experimental)

  • 'TRAPZ' : Trapezoidal, with the prescription by Sugimoto (1970) for non-adiabatic cases

r_root_solver (default 'BRENT')

Root solver for real arithmetic; one of:

  • 'BRENT' : Brent’s method

c_root_solver (default 'RIDDERS')

Root solver for complex arithmetic; one of

  • 'RIDDERS' : Complex Ridders’ method

  • 'SECANT' : Secant method

  • 'SIMPLEX' : Simplex method

n_iter_max (default 50)

Maximum number of iterations in root-finding algorithm

matrix_type (default 'BLOCK’)

Storage type of system matrix; one of

  • 'BAND' : Band-structured

  • 'BLOCK' : Block-structured

deflate_roots (default .TRUE.)

Flag to use root deflation, which can avoid the same eigenfrequency being found multiple times

restrict_roots (default .TRUE.)

Flag to check each roots found lies within the bounds of the frequency scan

ad_search (default 'BRACKET')

Initial search method for adiabatic calculations; one of

  • 'BRACKET' : Bracket sign changes in the discriminant function

nad_search (default 'AD')

Initial search method for non-adiabatic calculations; one of

  • 'AD' : Use adiabatic eigenfrequencies

  • 'MINMOD' : Find minima in the modulus of the discriminant function, along the real-\(\omega\) axis

  • 'CONTOUR' : Find intersections between real and imaginary zero-contours of the discriminant function

See the Non-Adiabatic Calculations chapter for more details about these search methods.

tag_list (default '', which matches all)

Comma-separated list of &mode tags to match