2017年5月27日土曜日

学習環境

数学読本〈4〉数列の極限,順列/順列・組合せ/確率/関数の極限と微分法(松坂 和夫(著)、岩波書店)の第17章(関数の変化をとらえる - 関数の極限と微分法)、17.3(導関数とその計算)、曲線の接線の方程式、問33.を取り組んでみる。


    1. y1=3( x1 )

    2. ( 2,8 ) y+8=12( x+2 )

    3. ( 2,8 ) y'=2x2 y8=2( x+2 )

    4. ( 2, 16 3 ) y'=2 x 2 y 16 3 =8( x+2 )

    5. ( 1,1 ) y'=5 x 4 y1=5( x1 )

    6. ( 2,16 ) y'=4 x 3 y16=32( x+2 )

    7. y'=2x3 ( x 0 , x 0 2 3 x 0 ) y( x 0 2 3 x 0 )=( 2 x 0 3 )( x x 0 ) 4 x 0 2 +3 x 0 =( 2 x 0 3 )( 3 x 0 ) 4 x 0 2 +3 x 0 =6 x 0 2 x 0 2 9+3 x 0 x 0 2 6 x 0 +5=0 ( x 0 1 )( x 0 5 )=0 x 0 =1, y 0 =2 x 0 =5, y 0 =10 y+2=( x1 ) y10=7( x5 )

    8. y'=3 x 2 ( x 0 , x 0 3 ) y x 0 3 =3 x 0 2 ( x x 0 ) 16 x 0 3 =3 x 0 3 x 0 3 =8 x 0 =2 y+8=12( x+2 )

    9. y'=3 x 2 ( x 0 , x 0 3 ) y x 0 3 =3 x 0 2 ( x x 0 ) 5 x 0 3 =3 x 0 2 ( 1 x 0 ) 5 x 0 3 =3 x 0 2 3 x 0 3 2 x 0 3 3 x 0 2 +5=0 ( x 0 +1 )( 2 x 0 2 5 x 0 +5 )=0 x 0 =1 y+1=3( x+1 )

    10. ( 4,2 ) y'= 1 2 x 1 2 y2= 1 4 ( x4 )

    11. y'= x 1 2 x 1 2 =2 x= 1 4 y1=2( x 1 4 )

    12. y'= 2·2x ( 1+ x 2 ) 2 = 4x ( 1+ x 2 ) 2 y1=( x1 )

コード(Emacs)

Python 3

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

from sympy import pprint, symbols, sqrt, Derivative, solve, plot

x = symbols('x')
expr = 2 * sqrt(x)
pprint(expr)

d = Derivative(expr, x)
pprint(d)

s = solve(d.doit() - 2, x)
pprint(s)

x0 = s[0]
y0 = expr.subs({x: x0})
f = 2 * (x - x0) + y0
pprint(f)

plot(f).save('sample33.svg')

入出力結果(Terminal, IPython)

$ ./sample33.py
2⋅√x
d       
──(2⋅√x)
dx      
[1/4]
2⋅x + 1/2
$

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="-10">
<label for="x2">x2 = </label>
<input id="x2" type="number" value="10">
<br>
<label for="y1">y1 = </label>
<input id="y1" type="number" value="-10">
<label for="y2">y2 = </label>
<input id="y2" type="number" value="10">

<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="sample33.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'),
    inputs = [input_r, input_dx, input_x1, input_x2, input_y1, input_y2],
    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 f = (x) => 2 / (1 + x ** 2),
    f1 = (x, x0, y0) => (-4 * x0 / (1 + x0 ** 2) ** 2) * (x - x0) + y0;

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);
    
    if (r === 0 || dx === 0 || x1 > x2 || y1 > y2) {
        return;
    }

    let points = [];
    
    for (let x = x1; x <= x2; x += dx) {
        let y = f(x);

        if (Math.abs(y) < Infinity) {
            points.push([x, y]);
        }
    }
    
    let lines = [];
    for (let x = x1; x <= x2; x += 100 * dx) {
        let y = f(x),
            y1 = f1(x1, x, y),
            y2 = f1(x2, x, y);

        if (Math.abs(y1) < Infinity && Math.abs(y2) < Infinity) {
            lines.push([x1, y1, x2, y2]);
        }
    }
    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, i) => i <= 1 ? 'black' : 'blue');
    
    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', 'red');
    
    svg.append('g')
        .attr('transform', `translate(0, ${height - padding})`)
        .call(xaxis);

    svg.append('g')
        .attr('transform', `translate(${padding}, 0)`)
        .call(yaxis);
};

inputs.forEach((input) => input.onchange = draw);
btn0.onclick = draw;
btn1.onclick = () => pre0.textContent = '';
draw();







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