MA97 Linear Solver

ma97_print_level:

Debug printing level for the linear solver MA97
The valid range for this integer option is ${\tt -inf} < {\tt ma97\_print\_level } < {\tt +inf}$ and its default value is 0 .

ma97_nemin:

Node Amalgamation parameter
Two nodes in elimination tree are merged if result has fewer than ma97_nemin variables. The valid range for this integer option is $1 \le {\tt ma97\_nemin } < {\tt +inf}$ and its default value is $8$ .

ma97_order:

Controls type of ordering used by HSL_MA97
The default value for this string option is "auto".
Possible values:

• auto: Use HSL_MA97 heuristic to guess best of AMD and METIS
• best: Try both AMD and MeTiS, pick best
• amd: Use the HSL_MC68 approximate minimum degree algorithm
• metis: Use the MeTiS nested dissection algorithm
• matched-auto: Use the HSL_MC80 matching with heuristic choice of AMD or METIS
• matched-metis: Use the HSL_MC80 matching based ordering with METIS
• matched-amd: Use the HSL_MC80 matching based ordering with AMD

ma97_scaling:

Specifies strategy for scaling in HSL_MA97 linear solver
The default value for this string option is "dynamic".
Possible values:

• none: Do not scale the linear system matrix
• mc30: Scale all linear system matrices using MC30
• mc64: Scale all linear system matrices using MC64
• mc77: Scale all linear system matrices using MC77 [1,3,0]
• dynamic: Dynamically select scaling according to rules specified by ma97_scalingX and ma97_switchX options.

ma97_scaling1:

First scaling.
If ma97_scaling=dynamic, this scaling is used according to the trigger ma97_switch1. If ma97_switch2 is triggered it is disabled. The default value for this string option is "mc64".
Possible values:

• none: No scaling
• mc30: Scale linear system matrix using MC30
• mc64: Scale linear system matrix using MC64
• mc77: Scale linear system matrix using MC77 [1,3,0]

ma97_scaling2:

Second scaling.
If ma97_scaling=dynamic, this scaling is used according to the trigger ma97_switch2. If ma97_switch3 is triggered it is disabled. The default value for this string option is "mc64".
Possible values:

• none: No scaling
• mc30: Scale linear system matrix using MC30
• mc64: Scale linear system matrix using MC64
• mc77: Scale linear system matrix using MC77 [1,3,0]

ma97_scaling3:

Third scaling.
If ma97_scaling=dynamic, this scaling is used according to the trigger ma97_switch3. The default value for this string option is "mc64".
Possible values:

• none: No scaling
• mc30: Scale linear system matrix using MC30
• mc64: Scale linear system matrix using MC64
• mc77: Scale linear system matrix using MC77 [1,3,0]

ma97_small:

Zero Pivot Threshold
Any pivot less than ma97_small is treated as zero. The valid range for this real option is $0 \le {\tt ma97\_small } < {\tt +inf}$ and its default value is $1 \cdot 10^{-20}$ .

ma97_solve_blas3:

Controls if blas2 or blas3 routines are used for solve
The default value for this string option is "no".
Possible values:

• no: Use BLAS2 (faster, some implementations bit incompatible)
• yes: Use BLAS3 (slower)

ma97_switch1:

First switch, determine when ma97_scaling1 is enabled.
If ma97_scaling=dynamic, ma97_scaling1 is enabled according to this condition. If ma97_switch2 occurs this option is henceforth ignored. The default value for this string option is "od_hd_reuse".
Possible values:

• never: Scaling is never enabled.
• at_start: Scaling to be used from the very start.
• at_start_reuse: Scaling to be used on first iteration, then reused thereafter.
• on_demand: Scaling to be used after Ipopt request improved solution (i.e. iterative refinement has failed).
• on_demand_reuse: As on_demand, but reuse scaling from previous itr
• high_delay: Scaling to be used after more than 0.05*n delays are present
• high_delay_reuse: Scaling to be used only when previous itr created more that 0.05*n additional delays, otherwise reuse scaling from previous itr
• od_hd: Combination of on_demand and high_delay
• od_hd_reuse: Combination of on_demand_reuse and high_delay_reuse

ma97_switch2:

Second switch, determine when ma97_scaling2 is enabled.
If ma97_scaling=dynamic, ma97_scaling2 is enabled according to this condition. If ma97_switch3 occurs this option is henceforth ignored. The default value for this string option is "never".
Possible values:

• never: Scaling is never enabled.
• at_start: Scaling to be used from the very start.
• at_start_reuse: Scaling to be used on first iteration, then reused thereafter.
• on_demand: Scaling to be used after Ipopt request improved solution (i.e. iterative refinement has failed).
• on_demand_reuse: As on_demand, but reuse scaling from previous itr
• high_delay: Scaling to be used after more than 0.05*n delays are present
• high_delay_reuse: Scaling to be used only when previous itr created more that 0.05*n additional delays, otherwise reuse scaling from previous itr
• od_hd: Combination of on_demand and high_delay
• od_hd_reuse: Combination of on_demand_reuse and high_delay_reuse

ma97_switch3:

Third switch, determine when ma97_scaling3 is enabled.
If ma97_scaling=dynamic, ma97_scaling3 is enabled according to this condition. The default value for this string option is "never".
Possible values:

• never: Scaling is never enabled.
• at_start: Scaling to be used from the very start.
• at_start_reuse: Scaling to be used on first iteration, then reused thereafter.
• on_demand: Scaling to be used after Ipopt request improved solution (i.e. iterative refinement has failed).
• on_demand_reuse: As on_demand, but reuse scaling from previous itr
• high_delay: Scaling to be used after more than 0.05*n delays are present
• high_delay_reuse: Scaling to be used only when previous itr created more that 0.05*n additional delays, otherwise reuse scaling from previous itr
• od_hd: Combination of on_demand and high_delay
• od_hd_reuse: Combination of on_demand_reuse and high_delay_reuse

ma97_u:

Pivoting Threshold
See MA97 documentation. The valid range for this real option is $0 \le {\tt ma97\_u } \le 0.5$ and its default value is $1 \cdot 10^{-08}$ .

ma97_umax:

Maximum Pivoting Threshold
See MA97 documentation. The valid range for this real option is $0 \le {\tt ma97\_umax } \le 0.5$ and its default value is $0.0001$ .