/LAGMUL

Block Format Keyword Describes the Lagrange multiplier option.

Format

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/LAGMUL
Lagmod Lagopt Tol Alpha Alpha_s    

Definitions

Field Contents SI Unit Example
Lagmod Conjugates gradient pre-conditioning algorithm.
= 1 (Default)
Cholesky pre-conditioning
= 2
Polynomial first degree pre-conditioning

(Integer)

  
Lagopt Lagrange multiplier matrix scaling option.
= 0 (Default)
No scaling
= 1
Diagonal scaling
= 2
L2 norm matrix

(Integer)

  
Tol Convergence criteria.

Default = 1.E-11 (Real)

  
Alpha Iterative shift parameter.

Default = 0.001 (Real)

  
Alpha_s Initial shift value.

Default = 0.0 (Real)

  

Comments

  1. The Tol value defines a solver precision tolerance for the kinematical conditions treated by Lagrange multipliers:

    /BCS/LAGMUL, /GJOINT, /IMPVEL/LAGMUL, Lagrange Multiplier Method, /MPC, /RWALL/LAGMUL, and /RBODY/LAGMUL

  2. Alpha and Alpha_s are only used with Cholesky pre-conditioning, and may be used to optimize the matrix factorization speed and quality. These are parameters added to matrix diagonal to avoid failure of incomplete factorization algorithm.
  3. Kinematical conditions in Radioss solver may be optionally treated by a Lagrange multiplier method.

    These conditions are incompatible with standard kinematical conditions, and a warning is issued in Starter if an attempt to merge different solution methods for the same nodes is made.

    Otherwise, all Lagrange multiplier conditions are compatible; except in cases of physical incompatibility.