charlang/example/calCosineSimilarityBig.char

// work out the cosine similarity of two vectors(by big floats which have more precision)
// the result is in [0..1], which 1 indicates almost the same, 0 indicates not same at all

calCosineSimilarityBig := func(f1, f2) {

	l1 := len(f1)
	l2 := len(f2)

	if l1 != l2 {
		pl("two vectors' length are not same，length of f1: %v，length of f2: %v", l1, l2)
		return -1
	}

	rr := bigFloat(0.0)

	f1r := bigFloat(0.0)

	f2r := bigFloat(0.0)

	for i := 0; i < l1; i++ {
		f1Sub := bigFloat(f1[i])
		f2Sub := bigFloat(f2[i])

		rr += f1Sub * f2Sub
		f1r += f1Sub * f1Sub
		f2r += f2Sub * f2Sub
	}

	// tmp1 :=  // big.NewFloat(0).Mul(big.NewFloat(0).Sqrt(f1r), big.NewFloat(0).Sqrt(f2r))

	// tmp2 = big.NewFloat(0).Quo(rr, tmp1)

	// tmp3, _ = tmp2.Float64()

	return rr / (mathSqrt(f1r) * mathSqrt(f2r))
}


v1 := [1, 2, 3, 5]
v2 := [2.0, 2, 3, 4]

pln(calCosineSimilarityBig(v1, v2))

v3 := [9, 9, 8, 8]
pln(calCosineSimilarityBig(v1, v3))

pln("------------")

v4 := [111111, 2222222, 3333333, 55555555555555]
v5 := [2.0, 2, 3, 4]

pln(calCosineSimilarityBig(v4, v5))

v6 := [7877358736587356853, 9666666, 8.01, 999999999999]
pln(calCosineSimilarityBig(v4, v6))