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Math.pow()

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Math.pow() 函式回傳 baseexponent 次方(幂)值,也就是 baseexponent

語法

Math.pow(base, exponent)

參數

base
基數。
exponent
要乘上 base 幾次的指數。

回傳值

A number representing the given base taken to the power of the given exponent.

敘述

由於 pow()Math 的靜態方法,you always use it as Math.pow(), rather than as a method of a Math object you created(Math 並沒有建構子)。

示例

使用 Math.pow()

// simple
Math.pow(7, 2);    // 49
Math.pow(7, 3);    // 343
Math.pow(2, 10);   // 1024
// fractional exponents
Math.pow(4, 0.5);  // 2 (4 的平方根)
Math.pow(8, 1/3);  // 2 (8 的立方根)
Math.pow(2, 0.5);  // 1.4142135623730951 (2 的平方根)
Math.pow(2, 1/3);  // 1.2599210498948732 (2 的立方根)
// signed exponents
Math.pow(7, -2);   // 0.02040816326530612 (1/49)
Math.pow(8, -1/3); // 0.5
// signed bases
Math.pow(-7, 2);   // 49 (squares are positive)
Math.pow(-7, 3);   // -343 (cubes can be negative)
Math.pow(-7, 0.5); // NaN (negative numbers don't have a real square root)
// due to "even" and "odd" roots laying close to each other, 
// and limits in the floating number precision, 
// negative bases with fractional exponents always return NaN
Math.pow(-7, 1/3); // NaN 

規範

規範 狀態 註解
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.
ECMAScript 5.1 (ECMA-262)
The definition of 'Math.pow' in that specification.
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.pow' in that specification.
Standard  
ECMAScript Latest Draft (ECMA-262)
The definition of 'Math.pow' in that specification.
Draft  

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