website

commit 45fcb55febd603da9437b99ec1b8f59416daef96
parent 26e2bf5ead33ffeddaec796d4ac902f7a6e3192d
Author: hrryt <harry@mayesfield.uk>
Date:   Thu, 24 Sep 2026 16:28:31 +0100

Fix fraction formatting

Diffstat:
M
src/components/questions/AddingFractionsQuestion.jsx
 | 
4
++--
M
src/components/questions/QuadraticEquationQuestion.jsx
 | 
10
+++++-----
M
src/scripts/formatUtils.js
 | 
33
+++++++++++----------------------
M
src/scripts/mathsUtils.js
 | 
5
++++-

4 files changed, 22 insertions(+), 30 deletions(-)
diff --git a/src/components/questions/AddingFractionsQuestion.jsx b/src/components/questions/AddingFractionsQuestion.jsx
@@ -20,13 +20,13 @@ function getRandomFractions(seed) {
 export default function AddingFractionsQuestion({ seed, showAnswer }) {
   const [num1, denom1, num2, denom2] = getRandomFractions(seed++);
 
-  const question = formatFraction(num1, denom1) + ' + ' + formatFraction(num2, denom2);
+  const question = formatFraction(num1, denom1) + formatFraction(num2, denom2, { showPlus: true });
 
   const hcf = getHCF(denom1, denom2);
   const sum = (num1 * denom2 + num2 * denom1) / hcf;
   const lcm = denom1 * denom2 / hcf;
 
-  const answer = formatFraction(sum, lcm, {showOne: true, showZero: true, simplify: true});
+  const answer = formatFraction(sum, lcm, { simplify: true });
 
   return <Question question={question} answer={answer} showAnswer={showAnswer} />;
 }
diff --git a/src/components/questions/QuadraticEquationQuestion.jsx b/src/components/questions/QuadraticEquationQuestion.jsx
@@ -12,7 +12,7 @@ function formatQuadraticExpression(a, b, c) {
 
 function formatRoots(l, m, n, o) {
   if (m / l == o / n) return `x = ${formatFraction(-m, l, { simplify: true })}`;
-  if (-m / l == o / n) return `x = \\pm ${formatFraction(Math.abs(-m), l, { simplify: true })}`;
+  if (-m / l == o / n) return `x = \\pm ${formatFraction(Math.abs(m), l, { simplify: true })}`;
 
   return `x = ${formatFraction(-m, l, { simplify: true })} \\text{ or } x = ${formatFraction(-o, n, { simplify: true })}`;
 }
@@ -28,10 +28,10 @@ function formatFactors(l, m, n, o) {
   const hcf1 = Math.abs(getHCF(l, m))
   const hcf2 = Math.abs(getHCF(n, o))
   const frontCoefficient = hcf1 * hcf2
-  l = l / hcf1
-  m = m / hcf1
-  n = n / hcf2
-  o = o / hcf2
+  l /= hcf1
+  m /= hcf1
+  n /= hcf2
+  o /= hcf2
 
   const fFrontCoefficient = formatCoefficient(frontCoefficient, {showPlus: false, showOne: false, showZero: true})
   if (l == n && m == o) return `${fFrontCoefficient}${formatFactor(l, m)}^2`
diff --git a/src/scripts/formatUtils.js b/src/scripts/formatUtils.js
@@ -4,30 +4,19 @@ export function formatVec(arr) {
   return `\\bigl(\\begin{smallmatrix}${arr.join('\\\\')}\\end{smallmatrix}\\bigr)`
 }
 
-export function formatCoefficient(x, parameters = { showPlus: false, showOne: true, showZero: true, suffix: '' }) {
-  if (!parameters.showZero && x == 0) return '';
-  const plus = parameters.showPlus ? '+' : '';
-  const sign = x < 0 ? '-' : plus;
-  x = Math.abs(x);
-  parameters.showOne || x == 1 && (x = '');
-  return sign + x + (parameters.suffix ?? '');
+export function formatCoefficient(value, { absoluteString=null, showPlus=false, showOne=true, showZero=true, suffix='' } = { }) {
+  if (!showZero && value == 0) return '';
+  absoluteString ??= Math.abs(value);
+  const plus = showPlus ? '+' : '';
+  const sign = value < 0 ? '-' : plus;
+  showOne || value == 1 && (absoluteString = '');
+  return sign + absoluteString + (suffix ?? '');
 }
 
-// this thing is probably begging for bugs from simplification and zeroes.
-export function formatFraction(num, denom, parameters = { showPlus: false, showOne: true, showZero: true, simplify: false, suffix: '' }) {
-  if (!parameters.showZero && num == 0) return '';
-  if (getHCF(num, denom) == denom && parameters.simplify) return formatCoefficient(simplifyFraction(num, denom)[0], parameters)
-  const plus = parameters.showPlus ? '+' : ''
-  const sign = num / denom < 0 ? '-' : plus
-
-  num = Math.abs(num)
-  denom = Math.abs(denom);
-  [num, denom] = parameters.simplify ? simplifyFraction(num, denom) : [num, denom]
-  parameters.suffix || (parameters.suffix = '')
-
-  let x = `\\frac{${num}}{${denom}}`
-  parameters.showOne || num / denom == 1 && (x = '');
-  return sign + x + parameters.suffix
+export function formatFraction(num, denom, { simplify=false, showPlus=false, showOne=true, showZero=true, suffix='' } = { }) {
+  simplify && ([num, denom] = simplifyFraction(num, denom));
+  const absoluteString = denom == 1 ? null : `\\frac{${Math.abs(num)}}{${denom}}`;
+  return formatCoefficient(num / denom, { absoluteString: absoluteString, showPlus: showPlus, showOne: showOne, showZero: showZero, suffix: suffix });
 }
 
 export function formatLine(line) {
diff --git a/src/scripts/mathsUtils.js b/src/scripts/mathsUtils.js
@@ -1,6 +1,9 @@
 export function getHCF(a, b) {
+  if (b == 0) return a;
   if (a == 1 && b == 1) return 1;
-  return b == 0 ? a : getHCF(b, a % b);
+  const hcf = getHCF(b, a % b);
+  if (a * b < 0) return Math.abs(hcf);
+  return hcf;
 }
 
 export function simplifyFraction(num, denom) {