Merge pull request #249 from privacy-scaling-explorations/fix-pow

fix(utils): fix pow for negative exponent
privacy-scaling-explorations · Apr 18, 2024 · 6f78156 · 6f78156
2 parents a2df127 + 41b4fb8
commit 6f78156
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/packages/utils/src/f1-field.ts b/packages/utils/src/f1-field.ts
@@ -202,6 +202,11 @@ export default class F1Field {
             return this.one
         }
 
+        if (e < 0n) {
+            base = this.inv(base)
+            e = -e
+        }
+
         const n = scalar.bits(e)
 
         if (n.length === 0) {

diff --git a/packages/utils/tests/f1-field.test.ts b/packages/utils/tests/f1-field.test.ts
@@ -110,7 +110,7 @@ describe("F1Field", () => {
         expect(field.isZero(b)).toBeFalsy()
     })
 
-    it("Should pow into the finite field", () => {
+    it("Should pow into the finite field", async () => {
         const a = field.e(0n)
         const b = field.e(1n)
         const c = field.e(2n)
@@ -120,6 +120,8 @@ describe("F1Field", () => {
         expect(field.pow(b, c)).toBe(1n)
         expect(field.pow(a, b)).toBe(0n)
         expect(field.pow(a, d)).toBe(0n)
-        expect(field.pow(d, a)).toBe(1n)
+        expect(field.pow(0n, -1n)).toBe(0n)
+        expect(field.pow(2n, -1n)).toBe(field.inv(2n))
+        expect(field.pow(5n, -30n)).toBe(1n)
     })
 })