December 2016
Intermediate to advanced
440 pages
9h 44m
Japanese
Content preview from アルゴリズムクイックリファレンス 第2版
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42
■
3
章 アルゴリズムの構成要素
●
0x407851ef: 3.8800008
ランダムに選んだ
32
ビット値に対応する浮動小数点値を次に示す。
●
0x1aec9fae: 9.786529E-23
●
0x622be970: 7.9280355E20
●
0x18a4775b: 4.2513525E-24
32
ビット浮動小数点値では、
1
ビットが符号に、
8
ビットが指数に、そして
23
ビッ
トが仮数（
mantissa
や
significand
などと呼ぶ）に使われる。
Java
の浮動小数点表
現では、「
2
のべきは、指数部のビットを正数として解釈して決定され、その正数か
らバイアスを差し引く。
float
型では、バイアスは
126
である。」（
Venners, 1996
）
貯えられた指数が
128
だと、実際の指数の値は、
128
−
126
、すなわち
2
となる。
最大の精度を得るために、仮数部は常に正規化されて、最左桁は常に
1
とされる。
このビットは、実際に貯えられなくて
もよいが、
FPU
によって数の一部だと理解さ
れる。前の例で仮数は、
0.[1]11110000101000111101100 = [1/2] + 1/4 + 1/8 + 1/16 + 1/32 + 1/1,024+ 1/4,096 +
1/65,536 + 1/131,072 + 1/262,144 + 1/524,288 + 1/2,097,152 +1/4,194,304
となり、小数点以下の和を完全に計算すれば、正確な値は
0.970000028610229 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.