mphinputmatrix

Add a matrix system for linear solvers.

mphinputmatrix(model,str,soltag,soltypetag)

mphinputmatrix(model,str,soltag,soltypetag) adds the system matrices and vectors stored in the MATLAB® structure str to the model. The system matrices is associated to the linear solver configuration defined with the tag soltag and solved with the solver defined with the tag soltypetag.

soltypetag can only be one of the following solver type: Stationary, Eigenvalue, Time.

A valid structure for a stationary solver includes the following fields:

Table 6-11: Property/Value Pairs for the mphint2 Command.
Field name	Description
K	Stiffness matrix
L	Load vector
M	Constraint vector
N	Constraint Jacobian

A valid structure for a time-dependent/ eigenvalue solver includes the following fields:

Table 6-12: Property/Value Pairs for the mphint2 Command.
Field name	Description
K	Stiffness matrix
L	Load vector
M	Constraint vector
N	Constraint Jacobian
D	Damping matrix
E	Mass matrix

There is also the possibility to include the constraint force Jacobian vector NF.

Once the matrix system is loaded in the model, the solver configuration is set ready to run.

The system matrices are not stored in the model when it is saved as an MPH-file or loaded into the COMSOL Desktop.

Create a model with a square geometry

model = ModelUtil.create('Model');

comp = model.component.create('comp1', true);

geom = comp.geom.create('geom1', 2);

geom.create('sq1', 'Square');

Add an Equation General Form physics interface

g = comp.physics.create('g', 'GeneralFormPDE', 'geom1');

g.prop('ShapeProperty').set('order', 1)

g.prop('ShapeProperty').set('boundaryFlux', false);

cons = g.create('cons1', 'Constraint', 1).set('R', 'u');

cons.selection.set([1 2]);

Create a mapped mesh

map = comp.mesh.create('mesh1').create('map1', 'Map');

map.create('dis1', 'Distribution').set('numelem', 2);

map.feature('dis1').selection.set([1 2]);

Set-up the study and the solver configuration for a stationary problem:

std = model.study.create('std1');

std.create('stat', 'Stationary');

sol = model.sol.create('sol1');

sol.study('std1');

sol.feature.create('st1', 'StudyStep').set('studystep', 'stat');

sol.feature.create('v1', 'Variables');

sol.feature.create('s1', 'Stationary');

Extract the linear stationary matrix system in MATLAB:

str = mphmatrix(model,'sol1','out',{'K','L','M','N'},...

'initmethod','sol','initsol','zero');

Change the linear system by scaling the stiffness matrix:

str.K = str.K*0.5;

Insert the system matrix back to the model:

mphinputmatrix(model,str,'sol1','s1')

Run the solver configuration:

model.sol('sol1').runAll;

mphmatrix, mphxmeshinfo