[IMP] functions: add LOG function

This commit adds the LOG function (logarithm of base N).

closes #5714

Task: 4547230
X-original-commit: 08ee2d3
Signed-off-by: Lucas Lefèvre (lul) <[email protected]>
Signed-off-by: Adrien Minne (adrm) <[email protected]>

Author: hokolomopo

src/functions/module_math.ts

@@ -844,6 +844,29 @@ export const LN = {
   isExported: true,
 } satisfies AddFunctionDescription;
 
+// -----------------------------------------------------------------------------
+// LOG
+// -----------------------------------------------------------------------------
+export const LOG: AddFunctionDescription = {
+  description: _t("The logarithm of a number, for a given base."),
+  args: [
+    arg("value (number)", _t("The value for which to calculate the logarithm.")),
+    arg("base (number, default=10)", _t("The base of the logarithm.")),
+  ],
+  compute: function (
+    value: Maybe<FunctionResultObject>,
+    base: Maybe<FunctionResultObject> = { value: 10 }
+  ): number {
+    const _value = toNumber(value, this.locale);
+    const _base = toNumber(base, this.locale);
+    assert(() => _value > 0, _t("The value (%s) must be strictly positive.", _value.toString()));
+    assert(() => _base > 0, _t("The base (%s) must be strictly positive.", _base.toString()));
+    assert(() => _base !== 1, _t("The base must be different from 1."));
+    return Math.log10(_value) / Math.log10(_base);
+  },
+  isExported: true,
+};
+
 // -----------------------------------------------------------------------------
 // MOD
 // -----------------------------------------------------------------------------

tests/functions/module_math.test.ts

@@ -1698,6 +1698,37 @@ describe("LN formula", () => {
   });
 });
 
+describe("LOG function", () => {
+  test("LOG takes 1-2 arguments", () => {
+    expect(evaluateCell("A1", { A1: "=LOG()" })).toBe("#BAD_EXPR");
+    expect(evaluateCell("A1", { A1: "=LOG(10)" })).toBe(1);
+    expect(evaluateCell("A1", { A1: "=LOG(10, 10)" })).toBe(1);
+    expect(evaluateCell("A1", { A1: "=LOG(10, 10, 0)" })).toBe("#BAD_EXPR");
+  });
+
+  test("Value argument bust be strictly positive", () => {
+    expect(evaluateCell("A1", { A1: "=LOG(0)" })).toBe("#ERROR");
+    expect(evaluateCell("A1", { A1: "=LOG(-1)" })).toBe("#ERROR");
+  });
+
+  test("Base argument must be positive and different from 1", () => {
+    expect(evaluateCell("A1", { A1: "=LOG(10, -1)" })).toBe("#ERROR");
+    expect(evaluateCell("A1", { A1: "=LOG(10, 0)" })).toBe("#ERROR");
+    expect(evaluateCell("A1", { A1: "=LOG(10, 1)" })).toBe("#ERROR");
+  });
+
+  test.each([
+    [1, 2, 0],
+    [100, 10, 2],
+    [16, 2, 4],
+    [5, 6, 0.898244402],
+    [125.15, 0.1, -2.097430854],
+  ])("function result =LOG(%s, %s)", (arg0: number, arg1: number, expectedResult: number) => {
+    const cellValue = evaluateCell("A1", { A1: `=LOG(${arg0}, ${arg1})` });
+    expect(cellValue).toBeCloseTo(expectedResult, 4);
+  });
+});
+
 describe("MOD formula", () => {
   test.each([
     ["-42", "-10", -2],