Rational numbers

typescript/rational-numbers/rational-numbers.ts

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+function isPrime(n: number): boolean {
+  if (n === 2) {
+    return true;
+  }
+  if (n < 2 || n % 2 === 0) {
+    return false;
+  }
+  for (var i = 3; i <= Math.sqrt(n); i += 2) {
+    if (n % i === 0) {
+      return false;
+    }
+  }
+  return true;
+}
+
+function* primes(): Generator<number> {
+  let i = 0;
+  while (true) {
+    if (!isPrime(i)) {
+      i++;
+      continue;
+    }
+    yield i++;
+  }
+}
+
+for (let prime of primes()) {
+  console.log("prime", prime);
+  if (prime > 1000) {
+    break;
+  }
+}
+
+export class Rational {
+  constructor(public numerator: number, public denominator: number) {
+    if (denominator < 0) {
+      this.numerator = numerator * -1;
+      this.denominator = denominator;
+    }
+  }
+
+  add(rational: Rational): Rational {
+    /* The sum of two rational numbers `r₁ = a₁/b₁` and `r₂ = a₂/b₂`
+     * is `r₁ + r₂ = a₁/b₁ + a₂/b₂ = (a₁ * b₂ + a₂ * b₁) / (b₁ * b₂)`. */
+    return new Rational(
+      this.numerator * rational.denominator +
+        this.denominator * rational.numerator,
+      rational.numerator * rational.denominator
+    );
+  }
+
+  sub(rational: Rational): Rational {
+    throw new Error("Remove this statement and implement this function");
+  }
+
+  mul(rational: Rational): Rational {
+    throw new Error("Remove this statement and implement this function");
+  }
+
+  div(rational: Rational): Rational {
+    throw new Error("Remove this statement and implement this function");
+  }
+
+  abs(): Rational {
+    throw new Error("Remove this statement and implement this function");
+  }
+
+  exprational(amount: number): Rational {
+    throw new Error("Remove this statement and implement this function");
+  }
+
+  expreal(amount: number): Rational {
+    throw new Error("Remove this statement and implement this function");
+  }
+
+  reduce(): Rational {
+    throw new Error("Remove this statement and implement this function");
+  }
+}