LordGhostX · July 5, 2021 15:33 · Jul 5, 2021
diff --git a/ap_gp_sequences.go b/ap_gp_sequences.go
@@ -0,0 +1,73 @@
+package sequences
+
+import (
+	"errors"
+	"math"
+)
+
+func calcNextSequence(a, b, c float64, n int, apSeq bool) (float64, error) {
+	if apSeq {
+		if c - b != b - a {
+			return 0, errors.New("not a valid sequence")
+		}
+		r := c - b
+		return a + (float64(n) - 1) * r, nil
+	} else {
+		if c / b != b / a {
+			return 0, errors.New("not a valid sequence")
+		}
+		r := c / b
+		return a * math.Pow(r, float64(n) - 1), nil
+	}
+}
+
+func calcNextSequences(a, b, c float64, n int, apSeq bool) ([]float64, error) {
+	seq := make([]float64, n)
+	for i := 0; i < n; i++ {
+		val, err := calcNextSequence(a, b, c, i + 4, apSeq)
+		if err != nil {
+			return nil, err
+		} else {
+			seq[i] = val
+		}
+	}
+	return seq, nil
+}
+
+func calcSplitSequences(arr []float64, apSeq bool) ([]float64, error) {
+	var seq []float64
+	for i := 0; i < len(arr); i+=3 {
+		a, b, c := arr[i], arr[i+1], arr[i+2]
+		d, err := calcNextSequence(a, b, c, 4, apSeq)
+		if err != nil {
+			return nil, err
+		} else {
+			seq = append(seq, a, b, c, d)
+		}
+	}
+	return seq, nil
+}
+
+func CalcAP(a, b, c float64) (float64, error) {
+	return calcNextSequence(a, b, c, 4, true)
+}
+
+func CalcGP(a, b, c float64) (float64, error) {
+	return calcNextSequence(a, b, c, 4, false)
+}
+
+func CalcAPs(a, b, c float64, n int) ([]float64, error) {
+	return calcNextSequences(a, b, c, n, true)
+}
+
+func CalcGPs(a, b, c float64, n int) ([]float64, error) {
+	return calcNextSequences(a, b, c, n, false)
+}
+
+func CalcSplitAPs(arr []float64) ([]float64, error) {
+	return calcSplitSequences(arr, true)
+}
+
+func CalcSplitGPs(arr []float64) ([]float64, error) {
+	return calcSplitSequences(arr, false)
+}