# グラフ計算機

> 複数の関数、極座標曲線、媒介変数曲線を描画し、移動とズーム、根、交点、極値、面積の探索ができます。

操作できるページ：https://www.calcopenly.com/ja/math/graphing-calculator
分野：数学の計算機

Plot up to six functions of x on one set of axes, alongside polar curves such as r = 1 + cos(θ) and parametric curves such as (cos(t), sin(2t)). Drag to pan, scroll or pinch to zoom, and hover to read each function's value, which is recomputed in 50-digit decimal at the pointer.

Below the plot, the calculator lists the roots, turning points and intersections visible in the current window, found by bisection on sign changes. It can also plot the derivative of the first function and shade the area under it between two limits, reporting the integral by Simpson's rule.

Trigonometric functions take radians here, as in most graphing software; type pi/2 rather than 90.

## 入力

- **f(x)**
- **x**

## 結果

- f(x) — 主な結果

## 計算例

### Cubic at 2

- f(x): x^3 - 3x
- x: 2
- **f(x): 2**
- 照合元：8 − 6

### Sine at π/2

- f(x): sin(x)
- x: pi/2
- **f(x): 1**
- 照合元：sin(π/2) = 1; the plotter works in radians

### Rational function

- f(x): 1/(x-1)
- x: 3
- **f(x): 0.5**
- 照合元：1/2

## よくある質問

### How do I find where two graphs intersect?

Enter both functions and look at the 'Points of interest' table under the plot. It reports numerical candidates in the visible window, with coordinates rounded to 8 significant figures; this display precision does not guarantee that accuracy. Sampling can miss tangencies or closely spaced intersections. Zoom or pan to inspect the region, and check important solutions in the original equations.

### Can it plot polar and parametric equations?

Yes. Start a line with r = to plot a polar curve in θ (for example r = 2 sin(3θ) draws a three-petal rose), or write a pair in brackets such as (cos(t), sin(t)) for a parametric curve, traced for t from −2π to 2π.

### Why does tan(x) have gaps?

tan(x) has vertical asymptotes at x = π/2 + kπ, where it jumps from +∞ to −∞. The plotter breaks the line wherever consecutive samples jump by more than one and a half screen heights, so it doesn't draw false vertical lines across the asymptotes.

### 「グラフ計算機」の精度はどのくらいですか？

精度は入力値と計算方法の前提に依存します。十進演算には有効数字50桁を使いますが、推定、数値計算手法、元データの精度はそれより低い場合があります。表示の丸め処理でこれらの制約がなくなるわけではありません。 独立した出典の解答と照合した計算例：3。 例えば、「Cubic at 2」は8 − 6と照合しています。

### この計算方法の出典は何ですか？

OpenStax Precalculus 2e — Functions, function notation and graphs; Implementation: adaptive sampling with discontinuity breaks; values at a point recomputed in 50-digit Decimal.

## 出典

- [OpenStax Precalculus 2e — Functions, function notation and graphs](https://openstax.org/books/precalculus-2e/pages/1-1-functions-and-function-notation)
- Implementation: adaptive sampling with discontinuity breaks; values at a point recomputed in 50-digit Decimal