diff --git a/src/lib.zig b/src/lib.zig
index f6271f001259f53a7721246a6b8e19cfb169a524..7e75ae14327fbff7c348c576765709aad89e3ce2 100644
--- a/src/lib.zig
+++ b/src/lib.zig
@@ -265,3 +265,7 @@ pub fn positionalInit(comptime T: type, args: FieldsTuple(T)) T {
     }
     return t;
 }
+
+pub fn d2index(d1len: usize, d1: usize, d2: usize) usize {
+    return (d1len * d2) + d1;
+}