public static long Dot(IndexedVector vec1, IndexedVector vec2)
{
if (ReferenceEquals(vec1, vec2))
{
return(CbocModel.DotSelf(vec1));
}
long product = 0;
var cursor1 = 0;
var cursor2 = 0;
while (cursor1 < vec1.Count && cursor2 < vec2.Count)
{
var i1 = vec1.Index[cursor1];
var i2 = vec2.Index[cursor2];
if (i2 > i1)
{
cursor1++;
}
else if (i1 > i2)
{
cursor2++;
}
else
{
product += vec1.Values[cursor1++] * vec2.Values[cursor2++];
}
}
return(product);
}
public float CosAngle(Vector vec1, Vector vec2)
{
var ivec1 = vec1 as IndexedVector;
var ivec2 = vec2 as IndexedVector;
if (ivec1 == null || ivec2 == null)
{
return(0);
}
long dotProduct = Dot(ivec1, ivec2);
long dotSelf1 = CbocModel.DotSelf(vec1);
long dotSelf2 = CbocModel.DotSelf(vec2);
return((float)(dotProduct / (Math.Sqrt(dotSelf1) * Math.Sqrt(dotSelf2))));
}