From 6fa624424bd9a73a8c21607837f4407191171a8c Mon Sep 17 00:00:00 2001
From: Ozzie Gooen <ozzieagooen@gmail.com>
Date: Mon, 30 Sep 2024 05:56:05 -0700
Subject: [PATCH 1/3] Adds modulo operator

---
 .../squiggle-lang/__tests__/library/number_test.ts |  7 +++++++
 packages/squiggle-lang/src/fr/number.ts            | 14 ++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/packages/squiggle-lang/__tests__/library/number_test.ts b/packages/squiggle-lang/__tests__/library/number_test.ts
index 65169242c5..59a4389d99 100644
--- a/packages/squiggle-lang/__tests__/library/number_test.ts
+++ b/packages/squiggle-lang/__tests__/library/number_test.ts
@@ -34,4 +34,11 @@ describe("Numbers", () => {
   testEvalToBe("Number.cumprod([1,5,3])", "[1,5,15]");
   testEvalToBe("Number.diff([1])", "[]");
   testEvalToBe("Number.diff([1,5,3])", "[4,-2]");
+  testEvalToBe("Number.mod(10, 3)", "1");
+  testEvalToBe("mod(10, 3)", "1");
+  testEvalToBe("Number.mod(15, 4)", "3");
+  testEvalToBe("mod(-10, 3)", "2");
+  testEvalToBe("mod(-5, 3)", "1");
+  testEvalToBe("mod(5, -3)", "2");
+  testEvalToBe("mod(-5, -3)", "1");
 });
diff --git a/packages/squiggle-lang/src/fr/number.ts b/packages/squiggle-lang/src/fr/number.ts
index abe5f4db20..1e84f11db0 100644
--- a/packages/squiggle-lang/src/fr/number.ts
+++ b/packages/squiggle-lang/src/fr/number.ts
@@ -75,6 +75,20 @@ export const library = [
     displaySection: "Algebra (Number)",
     fn: (x, y) => Math.pow(x, y),
   }),
+  maker.nn2n({
+    name: "mod",
+    displaySection: "Algebra (Number)",
+    examples: [
+      makeFnExample(`mod(10, 3)`),
+      makeFnExample(`mod(-10, 3)`),
+      makeFnExample(`mod(10, -3)`),
+    ],
+    description:
+      "modulo. Note that there is no '%' operator in Squiggle for this operation..",
+    fn: (x, y) => {
+      return ((x % y) + y) % y;
+    },
+  }),
   maker.n2n({
     name: "unaryMinus",
     displaySection: "Functions (Number)",

From 0df66aeec3478842f115bfb40029ee1e71a1a2a4 Mon Sep 17 00:00:00 2001
From: Ozzie Gooen <ozzieagooen@gmail.com>
Date: Mon, 30 Sep 2024 05:58:05 -0700
Subject: [PATCH 2/3] Added comment

---
 packages/squiggle-lang/src/fr/number.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/squiggle-lang/src/fr/number.ts b/packages/squiggle-lang/src/fr/number.ts
index 1e84f11db0..7ec45acb63 100644
--- a/packages/squiggle-lang/src/fr/number.ts
+++ b/packages/squiggle-lang/src/fr/number.ts
@@ -86,7 +86,7 @@ export const library = [
     description:
       "modulo. Note that there is no '%' operator in Squiggle for this operation..",
     fn: (x, y) => {
-      return ((x % y) + y) % y;
+      return ((x % y) + y) % y; //See: https://stackoverflow.com/questions/4467539/javascript-modulo-gives-a-negative-result-for-negative-numbers
     },
   }),
   maker.n2n({

From e6a8ac49fd4b6a2992ba04f3ccd89765289e337c Mon Sep 17 00:00:00 2001
From: Ozzie Gooen <ozzieagooen@gmail.com>
Date: Mon, 30 Sep 2024 06:15:00 -0700
Subject: [PATCH 3/3] Fixed modulo for negative numbers

---
 packages/squiggle-lang/__tests__/library/number_test.ts | 4 ++--
 packages/squiggle-lang/src/fr/number.ts                 | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/squiggle-lang/__tests__/library/number_test.ts b/packages/squiggle-lang/__tests__/library/number_test.ts
index 59a4389d99..2277d9d947 100644
--- a/packages/squiggle-lang/__tests__/library/number_test.ts
+++ b/packages/squiggle-lang/__tests__/library/number_test.ts
@@ -39,6 +39,6 @@ describe("Numbers", () => {
   testEvalToBe("Number.mod(15, 4)", "3");
   testEvalToBe("mod(-10, 3)", "2");
   testEvalToBe("mod(-5, 3)", "1");
-  testEvalToBe("mod(5, -3)", "2");
-  testEvalToBe("mod(-5, -3)", "1");
+  testEvalToBe("mod(5, -3)", "-1");
+  testEvalToBe("mod(-5, -3)", "-2");
 });
diff --git a/packages/squiggle-lang/src/fr/number.ts b/packages/squiggle-lang/src/fr/number.ts
index 7ec45acb63..29c5840076 100644
--- a/packages/squiggle-lang/src/fr/number.ts
+++ b/packages/squiggle-lang/src/fr/number.ts
@@ -84,9 +84,9 @@ export const library = [
       makeFnExample(`mod(10, -3)`),
     ],
     description:
-      "modulo. Note that there is no '%' operator in Squiggle for this operation..",
+      "modulo. This is the same as the '%' operator in Python. Note that there is no '%' operator in Squiggle for this operation.",
     fn: (x, y) => {
-      return ((x % y) + y) % y; //See: https://stackoverflow.com/questions/4467539/javascript-modulo-gives-a-negative-result-for-negative-numbers
+      return x - y * Math.floor(x / y);
     },
   }),
   maker.n2n({