学習環境
- Surface 3 (4G LTE)、Surface 3 タイプ カバー、Surface ペン(端末)
- Windows 10 Pro (OS)
- 数式入力ソフト(TeX, MathML): MathType
- MathML対応ブラウザ: Firefox、Safari
- MathML非対応ブラウザ(Internet Explorer, Microsoft Edge, Google Chrome...)用JavaScript Library: MathJax
- 参考書籍
ラング線形代数学(上)(S.ラング (著)、芹沢 正三 (翻訳)、ちくま学芸文庫)の1章(R^n におけるベクトル)、3(ベクトルのノルム)、練習問題10、11.を取り組んでみる。
cosθ = 1 (0 ≤ θ ≤ 1)のならば、θ = 0となるので、ベクトルAとBは同じ向きを持つ。
cosθ = 0 (0 ≤ θ ≤ 1)のならば、θ = πとなるので、ベクトルAとBは反対の向きを持つ。
距離の可換性について。
三角不等式について。
コード(Emacs)
Python 3
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from sympy import pprint, symbols, Matrix, solve
print('11.')
A = Matrix(symbols('a1 a2', real=True))
B = Matrix(symbols('b1 b2', real=True))
C = Matrix(symbols('c1 c2', real=True))
print((A - B).norm() == (B - A).norm())
X = (A - B).norm()
Y = (A - C).norm() + (B - C).norm()
for t in [X, Y]:
pprint(t)
print()
pprint(X <= Y)
入出力結果(Terminal, Jupyter(IPython))
$ ./sample10.py
11.
True
_________________________
╱ 2 2
╲╱ (a₁ - b₁) + (a₂ - b₂)
_________________________ _________________________
╱ 2 2 ╱ 2 2
╲╱ (a₁ - c₁) + (a₂ - c₂) + ╲╱ (b₁ - c₁) + (b₂ - c₂)
_________________________ _________________________ _____________
╱ 2 2 ╱ 2 2 ╱ 2
╲╱ (a₁ - b₁) + (a₂ - b₂) ≤ ╲╱ (a₁ - c₁) + (a₂ - c₂) + ╲╱ (b₁ - c₁) +
____________
2
(b₂ - c₂)
$
HTML5
<div id="graph0"></div> <pre id="output0"></pre> <label for="r0">r = </label> <input id="r0" type="number" min="0" value="0.5"> <label for="dx">dx = </label> <input id="dx" type="number" min="0" step="0.0001" value="0.001"> <br> <label for="x1">x1 = </label> <input id="x1" type="number" value="-5"> <label for="x2">x2 = </label> <input id="x2" type="number" value="5"> <br> <label for="y1">y1 = </label> <input id="y1" type="number" value="-5"> <label for="y2">y2 = </label> <input id="y2" type="number" value="5"> <br> <label for="a1">a1 = </label> <input id="a1" type="number" value="2"> <label for="a2">a2 = </label> <input id="a2" type="number" value="3"> <br> <label for="b1">b1 = </label> <input id="b1" type="number" value="-4"> <label for="b2">b2 = </label> <input id="b2" type="number" value="5"> <button id="draw0">draw</button> <button id="clear0">clear</button> <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.6/d3.min.js" integrity="sha256-5idA201uSwHAROtCops7codXJ0vja+6wbBrZdQ6ETQc=" crossorigin="anonymous"></script> <script src="sample10.js"></script>
JavaScript
let div0 = document.querySelector('#graph0'),
pre0 = document.querySelector('#output0'),
width = 600,
height = 600,
padding = 50,
btn0 = document.querySelector('#draw0'),
btn1 = document.querySelector('#clear0'),
input_r = document.querySelector('#r0'),
input_dx = document.querySelector('#dx'),
input_x1 = document.querySelector('#x1'),
input_x2 = document.querySelector('#x2'),
input_y1 = document.querySelector('#y1'),
input_y2 = document.querySelector('#y2'),
input_a1 = document.querySelector('#a1'),
input_a2 = document.querySelector('#a2'),
input_b1 = document.querySelector('#b1'),
input_b2 = document.querySelector('#b2'),
inputs = [input_r, input_dx, input_x1, input_x2, input_y1, input_y2,
input_a1, input_a2, input_b1, input_b2],
p = (x) => pre0.textContent += x + '\n',
range = (start, end, step=1) => {
let res = [];
for (let i = start; i < end; i += step) {
res.push(i);
}
return res;
};
let draw = () => {
pre0.textContent = '';
let r = parseFloat(input_r.value),
dx = parseFloat(input_dx.value),
x1 = parseFloat(input_x1.value),
x2 = parseFloat(input_x2.value),
y1 = parseFloat(input_y1.value),
y2 = parseFloat(input_y2.value),
a1 = parseFloat(input_a1.value),
a2 = parseFloat(input_a2.value),
b1 = parseFloat(input_b1.value),
b2 = parseFloat(input_b2.value);
if (r === 0 || dx === 0 || x1 > x2 || y1 > y2) {
return;
}
let points = [],
lines = [[0, 0, a1, a2, 'red'],
[0, 0, b1, b2, 'green'],
[a1, a2, b1, b2, 'blue']],
fns = [],
fns1 = [],
fns2 = [];
fns
.forEach((o) => {
let [f, color] = o;
for (let x = x1; x <= x2; x += dx) {
let y = f(x);
points.push([x, y, color]);
}
});
fns2
.forEach((o) => {
let [f, color] = o;
for (let x = x1; x <= x2; x += dx0) {
let g = f(x);
lines.push([x1, g(x1), x2, g(x2), color]);
}
});
let xscale = d3.scaleLinear()
.domain([x1, x2])
.range([padding, width - padding]);
let yscale = d3.scaleLinear()
.domain([y1, y2])
.range([height - padding, padding]);
let xaxis = d3.axisBottom().scale(xscale);
let yaxis = d3.axisLeft().scale(yscale);
div0.innerHTML = '';
let svg = d3.select('#graph0')
.append('svg')
.attr('width', width)
.attr('height', height);
svg.selectAll('line')
.data([[x1, 0, x2, 0], [0, y1, 0, y2]].concat(lines))
.enter()
.append('line')
.attr('x1', (d) => xscale(d[0]))
.attr('y1', (d) => yscale(d[1]))
.attr('x2', (d) => xscale(d[2]))
.attr('y2', (d) => yscale(d[3]))
.attr('stroke', (d) => d[4] || 'black');
svg.selectAll('circle')
.data(points)
.enter()
.append('circle')
.attr('cx', (d) => xscale(d[0]))
.attr('cy', (d) => yscale(d[1]))
.attr('r', r)
.attr('fill', (d) => d[2] || 'green');
svg.append('g')
.attr('transform', `translate(0, ${height - padding})`)
.call(xaxis);
svg.append('g')
.attr('transform', `translate(${padding}, 0)`)
.call(yaxis);
[fns, fns1, fns2].forEach((fs) => p(fs.join('\n')));
};
inputs.forEach((input) => input.onchange = draw);
btn0.onclick = draw;
btn1.onclick = () => pre0.textContent = '';
draw();
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