diff --git a/notebooks/problem0065.ipynb b/notebooks/problem0065.ipynb new file mode 100644 index 0000000..5782a09 --- /dev/null +++ b/notebooks/problem0065.ipynb @@ -0,0 +1,137 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "id": "bdec47c4", + "metadata": {}, + "source": [ + "# [Convergents of $e$](https://projecteuler.net/problem=65)\n", + "\n", + "Easy one-liner in SageMath." + ] + }, + { + "cell_type": "code", + "execution_count": 1, + "id": "8a93028c", + "metadata": {}, + "outputs": [ + { + "data": { + "text/plain": [ + "272" + ] + }, + "execution_count": 1, + "metadata": {}, + "output_type": "execute_result" + } + ], + "source": [ + "sum(continued_fraction(e).convergent(99).numerator().digits())" + ] + }, + { + "cell_type": "markdown", + "id": "396468b7", + "metadata": {}, + "source": [ + "If we wanted to compute the convergents ourselves, we could first make a generator for the partial denominators of the continued fraction of $e$." + ] + }, + { + "cell_type": "code", + "execution_count": 2, + "id": "bedc34c8", + "metadata": {}, + "outputs": [], + "source": [ + "from itertools import count, chain\n", + "\n", + "def partial_denominators_e(n):\n", + " yield 2\n", + " denominators = chain.from_iterable((1, 2 * k, 1) for k in count(1))\n", + " for (i, b) in enumerate(denominators):\n", + " if i >= n:\n", + " break\n", + " \n", + " yield b" + ] + }, + { + "cell_type": "markdown", + "id": "33288cd0", + "metadata": {}, + "source": [ + "Then write a function for computing a continued fraction from a sequence of partial denominators (outside of SageMath, you might want to use a [fraction type](https://docs.python.org/3/library/fractions.html))." + ] + }, + { + "cell_type": "code", + "execution_count": 3, + "id": "1f7bab23", + "metadata": {}, + "outputs": [], + "source": [ + "def cf(denominators):\n", + " a = next(denominators)\n", + " \n", + " try:\n", + " return a + 1 / cf(denominators)\n", + " except StopIteration:\n", + " return a" + ] + }, + { + "cell_type": "code", + "execution_count": 4, + "id": "5b8189b7", + "metadata": {}, + "outputs": [ + { + "data": { + "text/plain": [ + "272" + ] + }, + "execution_count": 4, + "metadata": {}, + "output_type": "execute_result" + } + ], + "source": [ + "sum(cf(partial_denominators_e(99)).numerator().digits())" + ] + }, + { + "cell_type": "markdown", + "id": "5778175d", + "metadata": {}, + "source": [ + "## Relevant sequences\n", + "* Numerators of convergents of $e$: [A007676](https://oeis.org/A007676)" + ] + } + ], + "metadata": { + "kernelspec": { + "display_name": "SageMath 9.5", + "language": "sage", + "name": "sagemath" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 3 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython3", + "version": "3.11.2" + } + }, + "nbformat": 4, + "nbformat_minor": 5 +}