public double userSimilarity(long userID1, long userID2)
{
int num4;
PreferenceArray array = this.dataModel.getPreferencesFromUser(userID1);
PreferenceArray array2 = this.dataModel.getPreferencesFromUser(userID2);
int num = array.length();
int num2 = array2.length();
if ((num <= 1) || (num2 <= 1))
{
return(double.NaN);
}
array = array.clone();
array2 = array2.clone();
array.sortByValue();
array2.sortByValue();
float num3 = 1f;
for (num4 = 0; num4 < num; num4++)
{
if (array2.hasPrefWithItemID(array.getItemID(num4)))
{
array.setValue(num4, num3);
num3++;
}
}
num3 = 1f;
for (num4 = 0; num4 < num2; num4++)
{
if (array.hasPrefWithItemID(array2.getItemID(num4)))
{
array2.setValue(num4, num3);
num3++;
}
}
array.sortByItem();
array2.sortByItem();
long num5 = array.getItemID(0);
long num6 = array2.getItemID(0);
int i = 0;
int num8 = 0;
double num9 = 0.0;
int num10 = 0;
while (true)
{
int num11 = (num5 < num6) ? -1 : ((num5 > num6) ? 1 : 0);
if (num11 == 0)
{
double num12 = array.getValue(i) - array2.getValue(num8);
num9 += num12 * num12;
num10++;
}
if (num11 <= 0)
{
if (++i >= num)
{
break;
}
num5 = array.getItemID(i);
}
if (num11 >= 0)
{
if (++num8 >= num2)
{
break;
}
num6 = array2.getItemID(num8);
}
}
if (num10 <= 1)
{
return(double.NaN);
}
return(1.0 - ((6.0 * num9) / ((double)(num10 * ((num10 * num10) - 1)))));
}