/// <summary>
/// returns a copy of Equation with the given additional VariableFactor
/// </summary>
/// <param name="vf"></param>
/// <returns></returns>
public Equation AddFactor(VariableFactor vf)
{
var factors = new VariableFactor[this.Factors.Length + 1];
Array.Copy(Factors, 0, factors, 1, Factors.Length);
factors[0] = vf;
return(new Equation(LeftTerm, factors, Coefficient));
}
private Tableau PreprocessTableau(Tableau t)
{
//check if there is no need to preprocess the table
if (t.Equations.All(e => e.LeftTerm.Type == VariableType.Target || e.Coefficient >= 0))
{
return(t);
}
var eqs = new Equation[t.Equations.Length];
var tVar = Variable.Problem(0);
for (var i = 0; i < eqs.Length - 1; i++)
{
eqs[i] = t.Equations[i].AddFactor(new VariableFactor(tVar, 1));
}
var f = new VariableFactor[t.Equations[0].Factors.Length];
for (var i = 0; i < f.Length; i++)
{
f[i] = new VariableFactor(t.Equations[0].Factors[i].Variable, 0);
}
var target = new Equation(Variable.Target(), f, 0);
target = target.AddFactor(new VariableFactor(tVar, -1));
eqs[eqs.Length - 1] = target;
t = new Tableau(eqs);
for (var i = 0; i < eqs.Length; i++)
{
if (t[i].LeftTerm.Type != VariableType.Target && t[i].Coefficient < 0)
{
t = NextTableau(t, tVar, t[i].LeftTerm);
}
}
SolveTableau(ref t);
var mainEquations = new Equation[t.Equations.Length];
for (var i = 0; i < mainEquations.Length - 1; i++)
{
mainEquations[i] = t.Equations[i].RemoveFactor(tVar);
}
var mainTarget = target.RemoveFactor(tVar);
mainEquations[mainEquations.Length - 1] = mainTarget;
return(new Tableau(mainEquations));
}
/// <summary>
/// Returns an Equation which has applied the given Equation to the current Equation. The LeftTerm is equal to the current.
/// </summary>
/// <param name="equation">An Equation whith a LeftTerm Variable that exists in the current Equation Summands</param>
/// <returns></returns>
public Equation Resolve(Equation equation)
{
var fac = this[equation.LeftTerm];
var vars = new VariableFactor[equation.Factors.Length];
for (var i = 0; i < vars.Length; i++)
{
vars[i] = (equation[i] * fac) + this[equation[i].Variable];
}
var coefficient = Coefficient + equation.Coefficient * fac;
return(new Equation(LeftTerm, vars, coefficient));
}
private VariableFactor[] GetFactorsByLine(Variable[] vars, string[] fCells, bool negate)
{
var f = new VariableFactor[vars.Length];
for (var i = 0; i < f.Length; i++)
{
var val = double.Parse(fCells[i]);
if (negate)
{
val = 0 - val;
}
f[i] = new VariableFactor(vars[i], val);
}
return(f);
}
public Equation Switch(Variable leftTerm)
{
var baseFac = (-1) / this[leftTerm];
var factors = new VariableFactor[Factors.Length];
var si = IndexOf(leftTerm);
factors[si] = new VariableFactor(LeftTerm, -baseFac);
for (var i = 0; i < Factors.Length; i++)
{
if (i != si)
{
factors[i] = Factors[i] * baseFac;
}
}
return(new Equation(leftTerm, factors, Coefficient * baseFac));
}
public Solver(StreamReader reader)
{
var cells = ReadAllLines(reader).Select(l => l.Split(';')).ToArray();
var vCnt = int.Parse(cells[0][0]);
var cCnt = int.Parse(cells[0][1]);
var pVars = new Variable[vCnt];
var sVars = new Variable[cCnt];
for (var i = 0; i < pVars.Length; i++)
{
pVars[i] = Variable.Problem(i + 1);
}
var eqs = new List <Equation>();
for (var i = 0; i < cCnt; i++)
{
var op = cells[i + 3][0];
var fCells = cells[i + 3].Skip(1).ToArray();
if (op == "<=" || op == "=")
{
eqs.Add(new Equation(Variable.Slack(i + 1), GetFactorsByLine(pVars, fCells, true), double.Parse(cells[i + 3][vCnt + 1])));
}
if (op == ">=" || op == "=")
{
eqs.Add(new Equation(Variable.Slack(i + 1), GetFactorsByLine(pVars, fCells, false), double.Parse(cells[i + 3][vCnt + 1])));
}
}
//target function
var tFactors = new VariableFactor[vCnt];
var minimize = cells[1][0].Contains("min");
for (var i = 0; i < tFactors.Length; i++)
{
var val = double.Parse(cells[1][i + 1]);
if (minimize)
{
val = -val;
}
tFactors[i] = new VariableFactor(pVars[i], val);
}
var targetVal = double.Parse(cells[1][vCnt + 1]);
if (minimize)
{
targetVal = -targetVal;
}
var target = new Equation(Variable.Target(), tFactors, targetVal);
eqs.Add(target);
_equations = eqs.ToArray();
}
public bool Equals(VariableFactor other)
{
return(Variable.Equals(other.Variable) && Factor.Equals(other.Factor));
}