lib: add `BigCubeRoot`

1 files changed, 23 insertions, 0 deletions

diff --git a/lib/cbrt_test.go b/lib/cbrt_test.go
new file mode 100644
index 0000000..a5722c8
--- /dev/null
+++ b/lib/cbrt_test.go
@@ -0,0 +1,23 @@
+// Copyright © 2021 siddharth ravikumar <s@ricketyspace.net>
+// SPDX-License-Identifier: ISC
+
+package lib
+
+import (
+	"math/big"
+	"testing"
+)
+
+func TestBigCubeRoot(t *testing.T) {
+	a := big.NewFloat(612)
+	acr := BigCubeRoot(a)
+	if acr == nil {
+		t.Errorf("Could not find cube root of %v\n", a)
+		return
+	}
+	expected := big.NewFloat(8.490184748)
+	if big.NewFloat(0).Sub(acr, expected).Cmp(bigCubeRootTolerance) != -1 {
+		t.Errorf("Could not find cube root of %v (%v)\n", a, acr)
+		return
+	}
+}