{"id":1591,"date":"2026-10-30T12:00:00","date_gmt":"2026-10-30T03:00:00","guid":{"rendered":"https:\/\/quantumsea.net\/?p=1591"},"modified":"2026-10-27T12:32:28","modified_gmt":"2026-10-27T03:32:28","slug":"qs-expm1-log1p-small-difference-20261024","status":"publish","type":"post","link":"https:\/\/quantumsea.net\/?p=1591","title":{"rendered":"expm1\u3068log1p\u3001\u5c0f\u3055\u306a\u5909\u5316\u304c\u8a08\u7b97\u9014\u4e2d\u3067\u30bc\u30ed\u306b\u306a\u308b\u7406\u7531"},"content":{"rendered":"<p>\u5c0f\u3055\u306a\u5909\u5316\u3092\u8a08\u7b97\u3057\u305f\u306f\u305a\u306a\u306e\u306b\u3001\u7b54\u3048\u304c\u30bc\u30ed\u306b\u306a\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001x\uff1d10\u306e\u30de\u30a4\u30ca\u30b916\u4e57\u3092\u5165\u308c\u3066\u300ce\u306ex\u4e57\u304b\u30891\u3092\u5f15\u304f\u300d\u3068\u3001\u6570\u5b66\u3067\u306f\u6b63\u306e\u5024\u306b\u306a\u308b\u306e\u306b\u3001\u901a\u5e38\u306e\u6d6e\u52d5\u5c0f\u6570\u70b9\u8a08\u7b97\u3067\u306f0\u3068\u8868\u793a\u3055\u308c\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u3088\u3046\u306a\u5f0f\u306b\u7528\u610f\u3055\u308c\u3066\u3044\u308b\u306e\u304c<strong>expm1<\/strong>\u3068<strong>log1p<\/strong>\u3067\u3059\u3002\u524d\u8005\u306fexp(x)\u22121\u3001\u5f8c\u8005\u306flog(1\uff0bx)\u3092\u6c42\u3081\u308b\u5c02\u7528\u95a2\u6570\u3067\u3059\u3002\u5f0f\u3092\u305d\u306e\u307e\u307e\u4e8c\u6bb5\u968e\u3067\u8a08\u7b97\u3059\u308b\u5834\u5408\u3068\u4f55\u304c\u9055\u3046\u306e\u304b\u3001Python\u306e\u6a19\u6e96\u30e9\u30a4\u30d6\u30e9\u30ea\u3068\u72ec\u81ea\u306e\u5b9f\u884c\u4f8b\u3067\u78ba\u304b\u3081\u307e\u3059\u3002<\/p>\n<section class=\"influvetor-quick-summary\">\n<p><strong>\u7c21\u5358\u306b\u307e\u3068\u3081\u308b\u3068\uff1f<\/strong><\/p>\n<ul>\n<li>\u6d6e\u52d5\u5c0f\u6570\u70b9\u3067\u306f\u30011\u306e\u8fd1\u304f\u306b\u8868\u305b\u308b\u5024\u306e\u9593\u9694\u304c\u3042\u308a\u307e\u3059\u3002\u5fae\u5c0f\u306a\u5909\u5316\u304c\u9014\u4e2d\u3067\u4e38\u3081\u3089\u308c\u308b\u3068\u3001\u6700\u5f8c\u306b\u5f15\u304d\u7b97\u3092\u3057\u3066\u3082\u53d6\u308a\u623b\u305b\u307e\u305b\u3093\u3002<\/li>\n<li>expm1(x)\u3068log1p(x)\u306f\u3001\u30bc\u30ed\u306b\u8fd1\u3044x\u304b\u3089\u5c0f\u3055\u306a\u7d50\u679c\u3092\u6c42\u3081\u308b\u305f\u3081\u306e\u95a2\u6570\u3067\u3059\u3002\u5358\u306bexp\u3084log\u3092\u547c\u3093\u3060\u5f8c\u3067\u8868\u793a\u6841\u6570\u3092\u5897\u3084\u3059\u65b9\u6cd5\u3068\u306f\u7570\u306a\u308a\u307e\u3059\u3002<\/li>\n<li>\u5c02\u7528\u95a2\u6570\u3078\u6e21\u3059\u524d\u306b\u5165\u529b\u306e\u5dee\u304c\u6d88\u3048\u3066\u3044\u308c\u3070\u3001\u56de\u5fa9\u306f\u3067\u304d\u307e\u305b\u3093\u3002\u5143\u306ex\u3092\u4fdd\u6301\u3057\u3001\u5165\u529b\u7bc4\u56f2\u3068\u4f7f\u3063\u3066\u3044\u308b\u6570\u5024\u578b\u3082\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/li>\n<\/ul>\n<\/section>\n<h2>1\u306e\u96a3\u306b\u3042\u308b\u6570\u307e\u3067\u3001\u9593\u9694\u304c\u3042\u308b<\/h2>\n<p>\u3053\u3053\u3067\u4f7f\u3046binary64\u306f\u30012\u9032\u6570\u3067\u6709\u9650\u306e\u6841\u6570\u3092\u4fdd\u5b58\u3059\u308b\u6d6e\u52d5\u5c0f\u6570\u70b9\u5f62\u5f0f\u3067\u3059\u3002\u6709\u52b9\u6841\u306f53\u30d3\u30c3\u30c8\u3067\u3001\u3042\u3089\u3086\u308b\u5b9f\u6570\u3092\u305d\u306e\u307e\u307e\u4fdd\u5b58\u3067\u304d\u308b\u308f\u3051\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u8a08\u7b97\u7d50\u679c\u304c\u8868\u305b\u308b\u5024\u306e\u9593\u306b\u6765\u305f\u3068\u304d\u306f\u3001\u8fd1\u304f\u306e\u5024\u3078\u4e38\u3081\u3089\u308c\u307e\u3059\u3002<\/p>\n<p>1.0\u3088\u308a\u5927\u304d\u3044\u5074\u3067\u3001\u6b21\u306b\u8868\u305b\u308b\u5024\u307e\u3067\u306e\u5dee\u306f2\u306e\u30de\u30a4\u30ca\u30b952\u4e57\u3001\u7d042.22\u00d710\u306e\u30de\u30a4\u30ca\u30b916\u4e57\u3067\u3059\u3002\u4eca\u56de\u306ex\uff1d1e-16\u306f\u305d\u306e\u534a\u5206\u3088\u308a\u5c0f\u3055\u3044\u305f\u3081\u3001\u901a\u5e38\u306e\u6700\u8fd1\u63a5\u4e38\u3081\u3067\u306f\u30011.0\uff0bx\u306f\u518d\u30731.0\u306b\u306a\u308a\u307e\u3059\u3002\u3053\u308c\u306f\u300c\u5c0f\u3055\u3059\u304e\u308b\u6570\u306f\u4f55\u3067\u30820\u306b\u306a\u308b\u300d\u3068\u3044\u3046\u8a71\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u30021e-16\u81ea\u4f53\u306f\u4fdd\u5b58\u3067\u304d\u3066\u3082\u30011.0\u306b\u52a0\u3048\u305f\u7d50\u679c\u3068\u3057\u3066\u306f\u3001\u305d\u306e\u5fae\u5c0f\u306a\u9055\u3044\u3092\u6b8b\u305b\u306a\u3044\u306e\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u9055\u3044\u306f\u3001\u8868\u793a\u306e\u554f\u984c\u3068\u533a\u5225\u3057\u307e\u3059\u3002\u5024\u304c\u5185\u90e8\u30671.0\u3078\u4e38\u3081\u3089\u308c\u305f\u5f8c\u306b\u3001\u5c0f\u6570\u70b9\u4ee5\u4e0b\u3092\u9577\u304f\u8868\u793a\u3057\u3066\u3082\u3001\u5931\u308f\u308c\u305f\u5dee\u306f\u623b\u308a\u307e\u305b\u3093\u3002<\/p>\n<h2>exp\u306e\u7d50\u679c\u3092\u4e38\u3081\u3066\u304b\u3089\u5f15\u304f\u3068\u3001\u5dee\u3060\u3051\u304c\u6d88\u3048\u308b<\/h2>\n<p>\u6570\u5b66\u3067\u306f\u3001\u30bc\u30ed\u306b\u8fd1\u3044x\u306b\u3064\u3044\u3066exp(x)\u306f1\u306b\u8fd1\u304f\u3001exp(x)\u22121\u306f\u304a\u3088\u305dx\u306b\u306a\u308a\u307e\u3059\u3002\u3068\u3053\u308d\u304c\u3001\u5148\u306bexp(x)\u306e\u7d50\u679c\u3092binary64\u3078\u4e38\u3081\u308b\u3068\u3001x\u304c\u5341\u5206\u5c0f\u3055\u3044\u5834\u5408\u3001\u305d\u306e\u7d50\u679c\u304c1.0\u306b\u306a\u3063\u3066\u3057\u307e\u3044\u307e\u3059\u3002\u7d9a\u3051\u30661.0\u3092\u5f15\u3051\u3070\u3001\u7d50\u679c\u306f0\u3067\u3059\u3002<\/p>\n<p>\u6ce8\u610f\u3057\u305f\u3044\u306e\u306f\u3001\u6700\u5f8c\u306e\u5f15\u304d\u7b97\u3060\u3051\u304c\u8aa4\u3063\u3066\u3044\u308b\u308f\u3051\u3067\u306f\u306a\u3044\u3053\u3068\u3067\u3059\u3002\u3059\u3067\u306b\u4e38\u3081\u3089\u308c\u305f1.0\u304b\u30891.0\u3092\u5f15\u304f\u51e6\u7406\u306f\u3001\u305d\u306e\u4e8c\u3064\u306e\u6570\u306b\u3064\u3044\u3066\u306f\u6b63\u78ba\u3067\u3059\u3002\u6c42\u3081\u305f\u304b\u3063\u305f\u5fae\u5c0f\u306a\u5dee\u306f\u3001\u305d\u306e\u524d\u306e\u6bb5\u968e\u3067\u5931\u308f\u308c\u3066\u3044\u307e\u3059\u3002\u8fd1\u3044\u5024\u306e\u5dee\u3092\u53d6\u308b\u3068\u3001\u5143\u306e\u5024\u306b\u3068\u3063\u3066\u306f\u5c0f\u3055\u306a\u4e38\u3081\u8aa4\u5dee\u304c\u3001\u5dee\u306b\u3068\u3063\u3066\u306f\u5927\u304d\u306a\u76f8\u5bfe\u8aa4\u5dee\u306b\u306a\u308b\u3053\u3068\u304c\u554f\u984c\u3067\u3059\u3002<\/p>\n<p><code>math.expm1(x)<\/code>\u306f\u3001\u3053\u306e\u5dee\u3092\u4e00\u3064\u306e\u95a2\u6570\u3068\u3057\u3066\u6c42\u3081\u307e\u3059\u3002\u5c0f\u3055\u306ax\u306b\u9069\u3057\u305f\u8a08\u7b97\u3092\u4f7f\u3048\u308b\u305f\u3081\u3001\u3044\u3063\u305f\u3093\u4e38\u3081\u305fexp(x)\u304b\u3089\u5358\u7d14\u306b1\u3092\u5f15\u304f\u65b9\u6cd5\u3067\u5931\u308f\u308c\u308b\u60c5\u5831\u3092\u6b8b\u305b\u307e\u3059\u3002\u5185\u90e8\u306e\u8a08\u7b97\u6cd5\u306f\u30e9\u30a4\u30d6\u30e9\u30ea\u3084\u74b0\u5883\u306b\u3088\u308b\u306e\u3067\u3001\u7279\u5b9a\u306e\u7d1a\u6570\u3092\u5fc5\u305a\u4f7f\u3046\u3068\u306f\u9650\u308a\u307e\u305b\u3093\u3002<\/p>\n<h2>\u540c\u3058\u5165\u529b\u3067\u8a08\u7b97\u3059\u308b\u3068\u3001\u4f55\u304c\u5909\u308f\u308b\u304b<\/h2>\n<p>\u4ee5\u4e0b\u306fQS\u3067Python 3.12.14\u30fbmacOS\u306e\u74b0\u5883\u3067\u5b9f\u884c\u3057\u305fbinary64\u306e\u4f8b\u3067\u3059\u3002\u8868\u3067\u306f\u8aad\u307f\u3084\u3059\u3044\u6841\u6570\u3078\u4e38\u3081\u3066\u3044\u307e\u3059\u3002<code>1e-16<\/code>\u306f10\u306e\u30de\u30a4\u30ca\u30b916\u4e57\u3092\u8868\u3059\u8868\u8a18\u3067\u3059\u3002<\/p>\n<div style=\"overflow-x:auto\">\n<table style=\"min-width:850px;white-space:nowrap;border-collapse:collapse\">\n<thead>\n<tr>\n<th style=\"padding:10px;text-align:left;border:1px solid #ccd\">\u5165\u529b x<\/th>\n<th style=\"padding:10px;text-align:left;border:1px solid #ccd\">exp(x)\u22121<\/th>\n<th style=\"padding:10px;text-align:left;border:1px solid #ccd\">expm1(x)<\/th>\n<th style=\"padding:10px;text-align:left;border:1px solid #ccd\">log(1\uff0bx)<\/th>\n<th style=\"padding:10px;text-align:left;border:1px solid #ccd\">log1p(x)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"padding:10px;border:1px solid #ccd\">1e-8<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d049.99999994e-9<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d041.000000005e-8<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d049.99999989e-9<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d049.99999995e-9<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:10px;border:1px solid #ccd\">1e-12<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d041.00008890e-12<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d041.00000000e-12<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d041.00008890e-12<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d041.00000000e-12<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:10px;border:1px solid #ccd\">1e-16<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">0<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d041e-16<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">0<\/td>\n<td style=\"padding:10px;border:1px solid #ccd\">\u7d041e-16<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>\u5165\u529b\u304c1e-12\u306e\u5834\u5408\u3001\u4e8c\u6bb5\u968e\u306eexp(x)\u22121\u3067\u306f\u3001\u540c\u3058\u5165\u529b\u309280\u6841\u7cbe\u5ea6\u3067\u8a08\u7b97\u3057\u305f\u53c2\u7167\u5024\u306b\u5bfe\u3059\u308b\u76f8\u5bfe\u8aa4\u5dee\u304c\u7d040.00889%\u3067\u3057\u305f\u3002\u7d76\u5bfe\u7684\u306b\u306f\u5c0f\u3055\u306a\u5dee\u3067\u3082\u3001\u6c42\u3081\u305f\u3044\u7d50\u679c\u81ea\u4f53\u304c\u5c0f\u3055\u3044\u3068\u3001\u7121\u8996\u3067\u304d\u308b\u304b\u3069\u3046\u304b\u306e\u5224\u65ad\u306f\u5909\u308f\u308a\u307e\u3059\u3002<\/p>\n<figure><img decoding=\"async\" src=\"https:\/\/quantumsea.net\/wp-content\/uploads\/2026\/10\/qs-expm1-log1p-small-difference-20261024-figure-98f023c1c0ff.png\" alt=\"x\u304c10\u306e\u30de\u30a4\u30ca\u30b916\u4e57\u306e\u4f8b\u3002exp\u3092\u8a08\u7b97\u3057\u30661\u3092\u5f15\u304f\u30680\u306b\u306a\u308a\u3001expm1\u3067\u306f\u7d0410\u306e\u30de\u30a4\u30ca\u30b916\u4e57\u304c\u6b8b\u308b\u3002\u5148\u306b1\u3068x\u3092\u8db3\u3057\u3066log\u3092\u53d6\u308b\u30680\u306b\u306a\u308a\u3001log1p\u3067\u306f\u7d0410\u306e\u30de\u30a4\u30ca\u30b916\u4e57\u304c\u6b8b\u308b\u3002\" style=\"max-width:100%;height:auto\"><figcaption>QS\u72ec\u81ea\u306e\u5b9f\u884c\u7d50\u679c\u3092\u6574\u7406\u3057\u305f\u8a08\u7b97\u7d4c\u8def\u3002x\uff1d1e-16\u3001binary64\u306e\u4f8b\u3002\u6570\u5b66\u7684\u306b\u7b49\u3057\u3044\u5f0f\u3067\u3082\u3001\u9014\u4e2d\u3067\u3069\u306e\u5024\u3092\u4e38\u3081\u308b\u304b\u306b\u3088\u3063\u3066\u3001\u6b8b\u308b\u5dee\u304c\u5909\u308f\u308a\u307e\u3059\u3002<\/figcaption><\/figure>\n<p>\u53c2\u7167\u8a08\u7b97\u306b\u306f\u3001\u5165\u529b\u306efloat\u3092<code>Decimal.from_float<\/code>\u3067\u305d\u306e\u307e\u307e80\u6841\u7cbe\u5ea6\u306e\u8a08\u7b97\u3078\u79fb\u3057\u3066\u3044\u307e\u3059\u3002\u5341\u9032\u8868\u8a18\u306e1e-12\u3092\u7406\u60f3\u7684\u306a\u5b9f\u6570\u3068\u3057\u3066\u6271\u3063\u305f\u5024\u3068\u306e\u6bd4\u8f03\u3067\u306f\u306a\u304f\u3001<strong>\u540c\u3058\u8868\u73fe\u6e08\u307f\u5165\u529b\u306b\u5bfe\u3059\u308b\u6f14\u7b97\u306e\u9055\u3044<\/strong>\u3092\u6bd4\u3079\u308b\u305f\u3081\u3067\u3059\u3002\u6700\u5f8c\u306e\u6570\u30d3\u30c3\u30c8\u306f\u5b9f\u884c\u74b0\u5883\u306b\u3088\u3063\u3066\u5909\u308f\u308a\u5f97\u308b\u305f\u3081\u3001\u3053\u306e\u8868\u3092\u3059\u3079\u3066\u306e\u6570\u5024\u30e9\u30a4\u30d6\u30e9\u30ea\u306e\u7d50\u679c\u4fdd\u8a3c\u3068\u3057\u3066\u306f\u4f7f\u3048\u307e\u305b\u3093\u3002<\/p>\n<h2>log1p\u306b\u306f\u30011\u3092\u8db3\u3059\u524d\u306ex\u3092\u6e21\u3059<\/h2>\n<p>log1p\u306elog\u306f\u81ea\u7136\u5bfe\u6570\u3067\u3059\u3002\u30bc\u30ed\u306b\u8fd1\u3044x\u3067\u306flog(1\uff0bx)\u3082\u304a\u3088\u305dx\u306b\u306a\u308a\u307e\u3059\u3002\u3057\u304b\u3057\u5148\u306b1.0\uff0bx\u304c1.0\u3078\u4e38\u3081\u3089\u308c\u308b\u3068\u3001log\u3078\u6e21\u308b\u306e\u306f1.0\u3067\u3042\u308a\u3001log(1.0)\u306f0\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p><code>math.log1p(x)<\/code>\u306b\u306f\u3001\u5143\u306ex\u3092\u305d\u306e\u307e\u307e\u6e21\u3057\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001\u3044\u3063\u305f\u3093<code>y = 1.0 + x<\/code>\u3092\u4f5c\u308a\u3001\u305d\u306e\u5f8c\u3067<code>math.log1p(y - 1.0)<\/code>\u3068\u66f8\u304d\u63db\u3048\u3066\u3082\u3001y\u304c\u3059\u3067\u306b1.0\u306a\u3089\u5165\u529b\u306f0\u3067\u3059\u3002\u95a2\u6570\u540d\u3092\u7f6e\u304d\u63db\u3048\u308b\u3060\u3051\u3067\u306f\u3001\u524d\u6bb5\u3067\u6d88\u3048\u305f\u60c5\u5831\u3092\u53d6\u308a\u623b\u305b\u307e\u305b\u3093\u3002<\/p>\n<p>\u5b9f\u88c5\u3092\u70b9\u691c\u3059\u308b\u3068\u304d\u306f\u3001\u6700\u7d42\u884c\u3060\u3051\u3067\u306a\u304f\u3001\u5c0f\u3055\u306a\u5909\u5316\u3092\u3069\u3053\u3067\u4f5c\u308a\u3001\u3069\u3053\u3067\u5927\u304d\u306a\u57fa\u6e96\u5024\u3078\u8db3\u3057\u305f\u304b\u3092\u8ffd\u3044\u307e\u3059\u3002\u5909\u5316\u91cfx\u3092\u72ec\u7acb\u3057\u3066\u4fdd\u6301\u3067\u304d\u308b\u306a\u3089\u3001\u305d\u306e\u5f62\u306e\u307e\u307e\u5c02\u7528\u95a2\u6570\u3078\u6e21\u3059\u3053\u3068\u304c\u9078\u629e\u80a2\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<h2>\u5c0f\u3055\u306a\u6e1b\u5c11\u91cf\u306b\u3082\u3001\u5f0f\u3092\u7d44\u307f\u66ff\u3048\u3066\u4f7f\u3048\u308b<\/h2>\n<p>\u4f8b\u3048\u3070\u3001\u975e\u8ca0\u306e\u5c0f\u3055\u306ax\u306b\u5bfe\u3057\u3066\u3001\u6b8b\u308b\u5272\u5408\u3092exp(\u2212x)\u3068\u7f6e\u3044\u305f\u6570\u5f0f\u30e2\u30c7\u30eb\u3092\u8003\u3048\u307e\u3059\u3002\u305d\u3053\u304b\u3089\u6e1b\u3063\u305f\u5272\u5408\u306f1\u2212exp(\u2212x)\u3067\u3059\u3002\u3053\u306e\u5024\u3092\u8a08\u7b97\u3057\u305f\u3044\u306a\u3089\u3001<code>-math.expm1(-x)<\/code>\u3068\u66f8\u304f\u3053\u3068\u3067\u30011\u306b\u8fd1\u3044\u4e8c\u3064\u306e\u5024\u3092\u6700\u5f8c\u306b\u5f15\u304f\u5f62\u3092\u907f\u3051\u3089\u308c\u307e\u3059\u3002<\/p>\n<p>x\uff1d1e-16\u306e\u3068\u304d\u3001\u3053\u306e\u5c02\u7528\u95a2\u6570\u3092\u4f7f\u3063\u305f\u7d50\u679c\u306f\u7d041e-16\u3067\u3059\u3002\u3053\u306e\u4f8b\u306f\u5f0f\u306e\u8a55\u4fa1\u65b9\u6cd5\u3092\u793a\u3059\u3082\u306e\u3067\u3001\u5b9f\u7269\u306e\u6e1b\u8870\u3084\u88c5\u7f6e\u6027\u80fd\u3092\u6e2c\u5b9a\u3057\u305f\u3082\u306e\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u6570\u5f0f\u304c\u5bfe\u8c61\u306b\u5408\u3063\u3066\u3044\u308b\u304b\u3068\u3044\u3046\u30e2\u30c7\u30eb\u306e\u554f\u984c\u3068\u3001\u305d\u306e\u6570\u5f0f\u3092\u7cbe\u5ea6\u3088\u304f\u8a08\u7b97\u3067\u304d\u308b\u304b\u3068\u3044\u3046\u6570\u5024\u8a08\u7b97\u306e\u554f\u984c\u306f\u3001\u305d\u308c\u305e\u308c\u78ba\u8a8d\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n<h2>\u5c02\u7528\u95a2\u6570\u3067\u3082\u89e3\u6c7a\u3057\u306a\u3044\u5883\u754c<\/h2>\n<p>expm1\u3084log1p\u3082\u6709\u9650\u7cbe\u5ea6\u3067\u52d5\u304d\u307e\u3059\u3002\u5165\u529b\u305d\u306e\u3082\u306e\u306e\u4e38\u3081\u3001\u3055\u3089\u306b\u5c0f\u3055\u306a\u5024\u3067\u306e\u8868\u73fe\u9650\u754c\u3001\u5927\u304d\u306a\u6b63\u306ex\u3067\u306e\u6307\u6570\u95a2\u6570\u306e\u30aa\u30fc\u30d0\u30fc\u30d5\u30ed\u30fc\u307e\u3067\u3001\u3059\u3079\u3066\u3092\u306a\u304f\u3059\u308f\u3051\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u5b9f\u6570\u3068\u3057\u3066log1p\u3092\u4f7f\u3048\u308b\u7bc4\u56f2\u306fx\uff1e\u22121\u3067\u3042\u308a\u3001Python\u306emath\u3067\u306f\u7bc4\u56f2\u5916\u3084\u5883\u754c\u306e\u6271\u3044\u3082\u78ba\u8a8d\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u5224\u65ad\u306e\u9806\u756a\u306f\u3001\u307e\u305a\u5fc5\u8981\u306a\u91cf\u304cexp(x)\u22121\u3084log(1\uff0bx)\u306e\u5f62\u306b\u306a\u3063\u3066\u3044\u308b\u304b\u3001\u6b21\u306bx\u304c\u30bc\u30ed\u306b\u8fd1\u3044\u9818\u57df\u3092\u901a\u308b\u304b\u3001\u305d\u3057\u3066\u5143\u306ex\u3092\u4fdd\u6301\u3057\u3066\u6e21\u305b\u308b\u304b\u3001\u3067\u3059\u3002\u5fc5\u8981\u306a\u8aa4\u5dee\u6c34\u6e96\u306b\u7167\u3089\u3057\u3066\u3001\u4ee3\u8868\u5024\u3060\u3051\u3067\u306a\u304f\u30bc\u30ed\u4ed8\u8fd1\u3084\u5883\u754c\u3067\u3082\u6bd4\u8f03\u3057\u307e\u3059\u3002\u6570\u5b66\u7684\u306a\u5f0f\u304c\u6b63\u3057\u304f\u3066\u3082\u3001\u305d\u306e\u307e\u307e\u306e\u8a08\u7b97\u9806\u5e8f\u304c\u6b32\u3057\u3044\u5c0f\u3055\u306a\u5dee\u3092\u6b8b\u305b\u308b\u3068\u306f\u9650\u308a\u307e\u305b\u3093\u3002<\/p>\n<h2>\u51fa\u5178<\/h2>\n<ul>\n<li><a href=\"https:\/\/docs.python.org\/3.14\/library\/math.html#math.expm1\">Python 3.14.9 documentation \u2014 math<\/a>\uff1aexpm1\u3001log1p\u3001ulp\u304a\u3088\u3073\u5b9f\u88c5\u4e0a\u306e\u6ce8\u610f\u3002\u78ba\u8a8d\u6642\u306e\u516c\u5f0f\u6587\u66f8\u306e\u7248\u8868\u793a\u3002<\/li>\n<li><a href=\"https:\/\/docs.python.org\/3.14\/tutorial\/floatingpoint.html\">Python 3.14.9 documentation \u2014 Floating-Point Arithmetic: Issues and Limitations<\/a>\uff1a2\u9032\u6d6e\u52d5\u5c0f\u6570\u70b9\u306e\u8868\u73fe\u3068\u4e38\u3081\u3002\u672c\u6587\u306e\u6570\u5024\u6bd4\u8f03\u30fb\u8868\u30fb\u56f3\u306fQS\u72ec\u81ea\u5b9f\u884c\u306b\u3088\u308b\u3082\u306e\u3002<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\u5c0f\u3055\u306a\u5909\u5316\u3092\u8a08\u7b97\u3057\u305f\u306f\u305a\u306a\u306e\u306b\u3001\u7b54\u3048\u304c\u30bc\u30ed\u306b\u306a\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001x\uff1d10\u306e\u30de\u30a4\u30ca\u30b916\u4e57\u3092\u5165\u308c\u3066\u300ce\u306ex\u4e57\u304b\u30891\u3092\u5f15\u304f\u300d\u3068\u3001\u6570\u5b66\u3067\u306f\u6b63\u306e\u5024\u306b\u306a\u308b\u306e\u306b\u3001\u901a\u5e38\u306e\u6d6e\u52d5\u5c0f\u6570\u70b9\u8a08\u7b97\u3067\u306f0\u3068\u8868\u793a\u3055\u308c\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002 \u3053\u306e\u3088 [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":1589,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":false,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[30],"tags":[323],"class_list":["post-1591","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-computing","tag-expm1-log1p"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/quantumsea.net\/wp-content\/uploads\/2026\/10\/qs-expm1-log1p-small-difference-20261024-featured-70b1b090173e.png","_links":{"self":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts\/1591","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1591"}],"version-history":[{"count":1,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts\/1591\/revisions"}],"predecessor-version":[{"id":1592,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts\/1591\/revisions\/1592"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/media\/1589"}],"wp:attachment":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1591"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1591"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1591"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}