void DoStageOne()
{
ScaleToMaxVal();
CreateStageOneSolver();
solver.ForbiddenPairs = forbiddenPairs;
solver.Solve();
if (solver.status != Status.Optimal)
{
this.status = Status.Infeasible;
return;
}
//this.CheckConstraints(this.solver.tableau.Getx());
//drive out artificials from the basis
tableau = solver.tableau;
var X = tableau.ReturnMatrix();
var x = tableau.GetSolution();
var basis = tableau.ReturnBasis();
Contract.Assume(X != null);
Contract.Assume(x != null);
Contract.Assume(basis != null);
int n = tableau.ReturnLengthOne();
int artificialsStart = nVars + nSlaksAndSurpluses;
int ioffset = 0;
Contract.Assume(x.Length <= basis.Length);
for (int i = 0; i < x.Length; i++, ioffset += n)
{
Contract.Assert(x.Length <= basis.Length);
Contract.Assert(i < basis.Length);
if (basis[i] >= artificialsStart)
{
if (x[i] > EpsilonForArtificials)
{
this.status = Status.Infeasible; //one of the artificials remains non-zero
return;
}
//find any non-zero number in non-artificials
int nonNulColumn = -1;
for (int j = 0; j < artificialsStart; j++)
{
Contract.Assume(ioffset + j >= 0); // ioffset gets decremented sometime
Contract.Assume(ioffset + j < X.Length); // ioffset gets decremented sometime
if (Math.Abs(X[ioffset + j]) > Epsilon)
{
nonNulColumn = j;
break;
}
}
if (nonNulColumn != -1)
{
tableau.Pivot(i, nonNulColumn);
}
else
{
//we have to cross out the i-th row because it is all zero
var newX = new double[(x.Length - 1) * n];
var newx = new double[x.Length - 1];
var ioOffset = 0;
var Ioffset = 0;
var io = 0;
for (var I = 0; I < x.Length; I++, Ioffset += n)
{
if (I != i)
{
Contract.Assume(io < newx.Length);
newx[io] = x[I];
for (int J = 0; J < n; J++)
{
Contract.Assume(Ioffset + J < X.Length);
var v = X[Ioffset + J];
Contract.Assume(ioffset + J < newX.Length);
newX[ioOffset + J] = v;
}
io++;
ioOffset += n;
}
}
var newBasis = new int[x.Length - 1];
io = 0;
for (var I = 0; I < x.Length; I++)
{
Contract.Assert(x.Length <= basis.Length);
if (I != i)
{
Contract.Assume(io < newBasis.Length);
newBasis[io] = basis[I];
io++;
}
}
//continue the loop on new X and on changed tableau
X = newX;
x = newx;
tableau.UpdateMatrix(X, x.Length, n);
tableau.SetSolution(x);
tableau.UpdateBasis(newBasis);
basis = newBasis;
i--;
ioffset -= n;
}
}
}
}
void DoStageOne()
{
ScaleToMaxVal();
CreateStageOneSolver();
solver.ForbiddenPairs = forbiddenPairs;
solver.Solve();
if (solver.status != Status.Optimal)
{
this.status = Status.Infeasible;
return;
}
//this.CheckConstraints(this.solver.tableau.Getx());
//drive out artificials from the basis
tableau = solver.tableau;
var X = tableau.ReturnMatrix();
var x = tableau.GetSolution();
var basis = tableau.ReturnBasis();
Contract.Assume(X != null);
Contract.Assume(x != null);
Contract.Assume(basis != null);
int n = tableau.ReturnLengthOne();
int artificialsStart = nVars + nSlaksAndSurpluses;
int ioffset = 0;
Contract.Assume(x.Length <= basis.Length);
for (int i = 0; i < x.Length; i++, ioffset += n)
{
Contract.Assert(x.Length <= basis.Length);
Contract.Assert(i < basis.Length);
if (basis[i] >= artificialsStart)
{
if (x[i] > EpsilonForArtificials)
{
this.status = Status.Infeasible; //one of the artificials remains non-zero
return;
}
//find any non-zero number in non-artificials
int nonNulColumn = -1;
for (int j = 0; j < artificialsStart; j++)
{
Contract.Assume(ioffset + j >= 0); // ioffset gets decremented sometime
Contract.Assume(ioffset + j < X.Length); // ioffset gets decremented sometime
if (Math.Abs(X[ioffset + j]) > Epsilon)
{
nonNulColumn = j;
break;
}
}
if (nonNulColumn != -1)
tableau.Pivot(i, nonNulColumn);
else
{
//we have to cross out the i-th row because it is all zero
var newX = new double[(x.Length - 1) * n];
var newx = new double[x.Length - 1];
var ioOffset = 0;
var Ioffset = 0;
var io = 0;
for (var I = 0; I < x.Length; I++, Ioffset += n)
{
if (I != i)
{
Contract.Assume(io < newx.Length);
newx[io] = x[I];
for (int J = 0; J < n; J++)
{
Contract.Assume(Ioffset + J < X.Length);
var v = X[Ioffset + J];
Contract.Assume(ioffset + J < newX.Length);
newX[ioOffset + J] = v;
}
io++;
ioOffset += n;
}
}
var newBasis = new int[x.Length - 1];
io = 0;
for (var I = 0; I < x.Length; I++)
{
Contract.Assert(x.Length <= basis.Length);
if (I != i)
{
Contract.Assume(io < newBasis.Length);
newBasis[io] = basis[I];
io++;
}
}
//continue the loop on new X and on changed tableau
X = newX;
x = newx;
tableau.UpdateMatrix(X, x.Length, n);
tableau.SetSolution(x);
tableau.UpdateBasis(newBasis);
basis = newBasis;
i--;
ioffset -= n;
}
}
}
}
