Why are elementwise additions much faster in separate loops than in a combined loop?
Suppose a1, b1, c1, and d1 point to heap memory, and my numerical code has the following core loop. const int n = 100000; for (int j = 0; j < n; j++) { a1[j] += b1[j]; c1[j] += d1[j]; } This loop is executed 10,000 times via another outer for loop. To speed it up, I changed the code to: for (int j = 0; j < n; j++) { a1[j] += b1[j]; } for (int j = 0; j < n; j++) { c1[j] += d1[j]; } Compiled on Micr
広ã知られã¦ã„ã‚‹insertion sortã®ã‚³ãƒ¼ãƒ‰ã¯é§„ç›®ã™ãŽã‚‹ - ã‚„ãã†ã‚‰ãŠâˆ’よã£ã¡ã‚ƒã‚“イカを食ã¹ãªãŒã‚‰å¹´åŽ1億円稼ã’ã‚‹(ã‹ã‚‚知れãªã„)仕事術
insertion sortã¯ã€ŒæŒ¿å…¥ã‚½ãƒ¼ãƒˆã€ã¨è¨³ã•ã‚Œã‚‹ã€‚(Wikipedia→ http://ja.wikipedia.org/wiki/%E6%8C%BF%E5%85%A5%E3%82%BD%E3%83%BC%E3%83%88 ) ■　日本語版 Wikipediaã®æ—¥æœ¬èªžã®ãƒšãƒ¼ã‚¸ã®ã‚³ãƒ¼ãƒ‰ã‚’引用ã™ã‚‹ã¨æ¬¡ã®ã‚ˆã†ã«ãªã£ã¦ã„る。 for (i = 1; i < n; i++) { tmp = data[i]; for (j = i; j > 0 && data[j-1] > tmp; j--) { data[j] = data[j-1]; } data[j] = tmp; }上ã®ã‚³ãƒ¼ãƒ‰ã§ã¯ã€å†…å´ã®ãƒ«ãƒ¼ãƒ—ã§insertã®å¿…è¦ãŒãªã‹ã£ãŸå ´åˆã§ã‚‚最後ã«data[j] = tmpã§tmp変数をwrite backã—ã¦ãŠã‚Šã€ã—ã‹ã‚‚ã€insertã®å¿…è¦ã®ãªã‹ã£ãŸå ´åˆã§ã‚‚j=iãŒ1回実行ã•ã‚Œã‚‹ã€‚ãれらã®æ„味ã«
1
リリースã€éšœå®³æƒ…å ±ãªã©ã®ã‚µãƒ¼ãƒ“スã®ãŠçŸ¥ã‚‰ã›
最新ã®äººæ°—エントリーã®é…ä¿¡
処ç†ã‚’実行ä¸ã§ã™
j次ã®ãƒ–ックマーク
kå‰ã®ãƒ–ックマーク
lã‚ã¨ã§èªã‚€
eコメント一覧を開ã
oページを開ã
{{#tags}}- {{label}}
{{/tags}}