void
Node2NodeContactL :: computeContactTangent(FloatMatrix &answer, CharType type, TimeStep *tStep)
{
answer.resize(7,7);
answer.zero();
FloatArray gap;
this->computeGap(gap, tStep);
if( gap.at(1) < 0.0 ) {
GaussPoint *gp = this->integrationRule->getIntegrationPoint(0);
FloatArray C;
this->computeCmatrixAt(gp, C, tStep);
int sz = C.giveSize();
C.times(this->area);
answer.addSubVectorCol(C, 1, sz + 1);
answer.addSubVectorRow(C, sz + 1, 1);
}
//TODO need to add a small number for the solver
for ( int i = 1; i <= 7; i++ ) {
answer.at(i,i) += 1.0e-8;
}
}
