public AccurateFactorial Accurate(AccurateFactorial n) //Most accurate method
//This method uses arrays instead of numbers
{
n = n.DisposeZero(n);
if (!n.BigEnough(n)) //Check if the number is higher than 1
{
if (n.value[0] > 0)
{
return(n);
}
else
{
return(new AccurateFactorial(1)); //only returns if the number is zero
}
}
// If I used "return n.multiply(Accurate(n.previous(n)), n)"
//the program worked much slower
AccurateFactorial m = new AccurateFactorial(n.value);
m.value = n.value;
m = n.previous(m);
AccurateFactorial m2 = new AccurateFactorial(Accurate(m).value);
return(n.multiply(m2, n));
}
//Check if the number is bigger than 1
public bool BigEnough(AccurateFactorial n)
{
if (n.value != null)
{
if (n.value.Length > 1 || n.value[0] > 1)
{
return(true);
}
}
return(false);
}
//Get multiplication of two big numbers
public AccurateFactorial multiply(params AccurateFactorial[] af)
{
AccurateFactorial mult = new AccurateFactorial();
for (int k = 0; k < 2; k++)
{
DisposeZero(af[0]); //prepare the numbers to work
}
//Set the size of new array
int length = af[0].value.Length + af[1].value.Length,
len1 = af[0].value.Length - 1, len2 = af[1].value.Length - 1;
mult.SetSize(length);
//implement the multiplication algorithm
length--; int reminder = 0;
int MaxLength = length;
for (int i = len1; i >= 0; i--)
{
for (int k = len2; k >= 0; k--)
{
int temp = reminder;
temp = af[0].value[i] * af[1].value[k];
reminder += temp / 10;
mult.value[length] += temp % 10;
mult.value[--length] += reminder;
reminder = 0;
}
MaxLength--;
length = MaxLength;
}
reminder = 0;
length = mult.value.Length - 1;
//Final summarization
for (int i = length; i > 0; i--)
{
mult.value[i - 1] += mult.value[i] / 10;
mult.value[i] = mult.value[i] % 10;
}
mult = DisposeZero(mult);
//Result
return(mult);
}
//Dispose from leading zeros
public AccurateFactorial DisposeZero(AccurateFactorial n)
{
if (n.value.Length > 1)
{
int len = 0, i = 0;
while (i < n.value.Length - 1 && n.value[i] == 0)
{
len++;
i++;
}
AccurateFactorial temp = new AccurateFactorial();
temp.SetSize(n.value.Length - len);
for (i = 0; i < n.value.Length - len; i++)
{
temp.value[i] = n.value[len + i];
}
return(temp);
}
return(n);
}
//Get previous number
public AccurateFactorial previous(AccurateFactorial n4)
{
if (!BigEnough(n4))
{
return(n4);
}
AccurateFactorial prev = new AccurateFactorial(n4.value);
int i = prev.Size() - 1;
if (i > -1)
{
while (i > 0 && prev.value[i] < 1)
{
prev.value[i]--;
prev.value[i] = (prev.value[i] + 10) % 10;
i--;
}
prev.value[i]--;
return(prev);
}
prev.value[i]--;
return(prev);
}
private void button1_Click(object sender, EventArgs e)
{
if (checkedListBox1.CheckedIndices.Count == 0) //check if algorithm is been chosen
{
MessageBox.Show("Choose algorithm!");
return;
}
if (textBox1.Text.Length < 1) //check if the represented number string is not empty
{
MessageBox.Show("Type integer number!");
return;
}
string checkstring = "0123456789";
try
{
//Check if the string only consists of the numerals
int SymbolsCount = 0;
foreach (char c in checkstring)
{
for (int i = 0; i < textBox1.Text.Length; i++)
{
if (textBox1.Text[i] == c)
{
SymbolsCount++;
}
}
}
if (SymbolsCount == textBox1.Text.Length)
{
AccurateFactorial n = new AccurateFactorial(textBox1.Text);
n = n.DisposeZero(n); //Dispose of extra zeros in the beginning
textBox1.Text = n.ToString();
//Choosing different methods depending on the selected algorithm
if (checkedListBox1.CheckedIndices[0] != 5)
{
if (long.TryParse(textBox1.Text, out long m))
{
switch (checkedListBox1.CheckedIndices[0])
{
case 0:
textBox2.Text = Factorial.GetFactorialWithCycles(m).ToString();
break;
case 1:
textBox2.Text = Factorial.GetFactorial(m).ToString();
break;
case 2:
textBox2.Text = Factorial.Approximation(m, "Ramanujan").ToString();
break;
case 3:
textBox2.Text = Factorial.Approximation(m, "Stirling").ToString();
break;
case 4:
textBox2.Text = Factorial.Approximation(m, "").ToString();
break;
}
if (long.TryParse(textBox2.Text, out long k))
{
if (k < 1 || m > 20)
{//Coud not calculate the factorial
textBox2.Text = "Error";
MessageBox.Show("The number is too big for the current method");
return;
}
}
}
return;
}
//check if the number is small enough
if (n.value.Length > 4 || (n.value.Length > 3 && n.value[0] > 6 && n.value[1] > 7))
{
textBox2.Text = $"The number {n.ToString()} is too big integer number (>=7500)";
return;
}
Factorial f = new Factorial(); //I made all methods to be used in the Factorial class
n = new AccurateFactorial(f.Accurate(n).value); //calculate using the best method
textBox2.Text = n.ToString(); //write result
}
else
{
textBox2.Text = "Error: the string must contain only numerals";
}
}
catch (Exception) {
MessageBox.Show("Unkown Error");
}
}