gcd and lcm don't return negative numbers

Doenet · Jan 14, 2025 · 355ab52 · 355ab52
1 parent 821aaae
commit 355ab52
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Showing 2 changed files with 54 additions and 2 deletions.
diff --git a/packages/doenetml-worker/src/components/MathOperators.js b/packages/doenetml-worker/src/components/MathOperators.js
@@ -1370,7 +1370,7 @@ function gcd(x, y, ...z) {
         return gcd(x, ...z);
     }
     if (!y) {
-        return x;
+        return Math.abs(x);
     }
     return gcd(y, x % y, ...z);
 }
@@ -1382,5 +1382,5 @@ function lcm(...z) {
 
     let g = gcd(...gcdArgs);
 
-    return prod / g;
+    return Math.abs(prod / g);
 }
diff --git a/packages/doenetml-worker/src/test/tagSpecific/mathoperators.test.ts b/packages/doenetml-worker/src/test/tagSpecific/mathoperators.test.ts
@@ -7509,6 +7509,32 @@ describe("Math operator tests", async () => {
         ]);
     });
 
+    it("gcd not negative", async () => {
+        let core = await createTestCore({
+            doenetML: `
+      <gcd name="gcd1a"><number>-135</number><number>81</number></gcd>
+      <gcd name="gcd1b"><number>135</number><number>-81</number></gcd>
+      <gcd name="gcd1c"><number>-135</number><number>-81</number></gcd>
+      <gcd name="gcd2a">-135 81 63</gcd>
+      <gcd name="gcd2b">135 -81 63</gcd>
+      <gcd name="gcd2c">135 81 -63</gcd>
+      <gcd name="gcd2d">-135 81 -63</gcd>
+      <gcd name="gcd2e">-135 -81 -63</gcd>
+      `,
+        });
+
+        let stateVariables = await returnAllStateVariables(core);
+
+        expect(stateVariables["/gcd1a"].stateValues.value.tree).eq(27);
+        expect(stateVariables["/gcd1b"].stateValues.value.tree).eq(27);
+        expect(stateVariables["/gcd1c"].stateValues.value.tree).eq(27);
+        expect(stateVariables["/gcd2a"].stateValues.value.tree).eq(9);
+        expect(stateVariables["/gcd2b"].stateValues.value.tree).eq(9);
+        expect(stateVariables["/gcd2c"].stateValues.value.tree).eq(9);
+        expect(stateVariables["/gcd2d"].stateValues.value.tree).eq(9);
+        expect(stateVariables["/gcd2e"].stateValues.value.tree).eq(9);
+    });
+
     it("lcm", async () => {
         let core = await createTestCore({
             doenetML: `
@@ -7529,6 +7555,32 @@ describe("Math operator tests", async () => {
         ]);
     });
 
+    it("lcm not negative", async () => {
+        let core = await createTestCore({
+            doenetML: `
+      <lcm name="lcm1a"><number>-135</number><number>81</number></lcm>
+      <lcm name="lcm1b"><number>135</number><number>-81</number></lcm>
+      <lcm name="lcm1c"><number>-135</number><number>-81</number></lcm>
+      <lcm name="lcm2a">-135 81 63</lcm>
+      <lcm name="lcm2b">135 -81 63</lcm>
+      <lcm name="lcm2c">135 81 -63</lcm>
+      <lcm name="lcm2d">-135 81 -63</lcm>
+      <lcm name="lcm2e">-135 -81 -63</lcm>
+      `,
+        });
+
+        let stateVariables = await returnAllStateVariables(core);
+
+        expect(stateVariables["/lcm1a"].stateValues.value.tree).eq(405);
+        expect(stateVariables["/lcm1b"].stateValues.value.tree).eq(405);
+        expect(stateVariables["/lcm1c"].stateValues.value.tree).eq(405);
+        expect(stateVariables["/lcm2a"].stateValues.value.tree).eq(2835);
+        expect(stateVariables["/lcm2b"].stateValues.value.tree).eq(2835);
+        expect(stateVariables["/lcm2c"].stateValues.value.tree).eq(2835);
+        expect(stateVariables["/lcm2d"].stateValues.value.tree).eq(2835);
+        expect(stateVariables["/lcm2e"].stateValues.value.tree).eq(2835);
+    });
+
     it("extract parts of math expression", async () => {
         let core = await createTestCore({
             doenetML: `