internal void CheckAnswer(Equation eqn, List <int> coefs)
{
if (coefs.Count != eqn.LeftSide.Count + eqn.RightSide.Count)
{
throw new BalancerException("Assertion error: Mismatched length");
}
var allzero = true;
foreach (var coef in coefs)
{
allzero = allzero && coef == 0;
}
if (allzero)
{
throw new BalancerException("Assertion error: All-zero solution");
}
foreach (var elem in eqn.GetElements())
{
var sum = 0;
var j = 0;
foreach (var term in eqn.LeftSide)
{
sum = CheckedAdd(sum, CheckedMultiply(term.CountElement(elem), coefs[j]));
j++;
}
foreach (var term in eqn.RightSide)
{
sum = CheckedAdd(sum, CheckedMultiply(term.CountElement(elem), -coefs[j]));
j++;
}
if (sum != 0)
{
throw new BalancerException("Assertion error: Incorrect balance");
}
}
}
public void Solve(string input)
{
// Clear output
ErrorMessage = "";
EquationHtml = new HtmlTag("div");
CodeOutputHtml = new HtmlTag("div");
var utils = new Utils();
// Parse equation
Equation eq = null;
try
{
eq = new Parser(input).ParseEquation();
}
catch (BalancerException bex)
{
ErrorMessage = "Syntax error: " + bex.Message;
var start = bex.Start;
var end = bex.End.HasValue ? bex.End.Value : bex.Start;
var separators = new List <char> {
' ', '\t'
};
while (end > start && separators.IndexOf(input[end - 1]) != -1)
{
end--; // Adjust position to eliminate whitespace
}
if (start == end)
{
end++;
}
CodeOutputHtml.AppendText(input.Substring(0, start));
if (end <= input.Length)
{
CodeOutputHtml.Append(utils.CreateElement("u", input.Substring(start, end)));
CodeOutputHtml.AppendText(input.Substring(end, input.Length));
}
else
{
CodeOutputHtml.Append(utils.CreateElement("u", " "));
}
}
catch (Exception ex)
{
ErrorMessage = "Syntax error: " + ex.Message;
return;
}
try
{
var matrix = utils.BuildMatrix(eq);
utils.Solve(matrix);
var coefs = utils.ExtractCoefficients(matrix);
utils.CheckAnswer(eq, coefs);
EquationHtml.Append(eq.ToHtml(coefs));
EquationText = eq.ToString(coefs);
}
catch (Exception ex)
{
ErrorMessage = ex.ToString();
}
}