1 files changed, 41 insertions, 0 deletions
diff --git a/eqpct.go b/eqpct.go
new file mode 100644
index 0000000..d830049
--- /dev/null
+++ b/eqpct.go
@@ -0,0 +1,41 @@
+package badtudexo 
+
+import (
+	"errors"
+	"fmt"
+)
+
+// Given a list of base, percent and the result and a tolerance return a list
+// of indices where outside this tolerance pct. For instance, given a base of
+// [100, 50, 200], percents of [ 10, 10, 10 ], and a tolerance either way of
+// 1%, return all in result which are not between 9% and 11% of the
+// corresponding index of base: if res were [10, 2, 19], return [1], as the 
+// 2nd (1st w/ zero-indexing) elem is the only one outside the allowed pcts.
+func EqPct(base, pct, res []float64, tol float64) ([]int, error) {
+	var ret []int
+	var allgood bool = true
+	if len(base) != len(pct) {
+		return nil, errors.New("len(base) != len(pct)")
+	}
+
+	if len(pct) != len(res) {
+		return nil, errors.New("len(pct) != len(res)")
+	}
+
+	for i := 0; i < len(pct); i++ {
+		min := base[i] * ((pct[i] - tol) / 100)
+		max := base[i] * ((pct[i] + tol) / 100)
+
+		if res[i] < min || res[i] > max {
+			// fmt.Printf("Min [%v] < Res [%v] > Max [%v]\n", min, res[i], max)
+			allgood = false
+			ret = append(ret, i)
+		}
+	}
+
+	if allgood {
+		// fmt.Println("EqPct: all good!")
+	}
+
+	return ret, nil
+}