{"id":2354,"date":"2020-05-03T17:10:55","date_gmt":"2020-05-03T15:10:55","guid":{"rendered":"https:\/\/www.mathweb.fr\/euclide\/?page_id=2354"},"modified":"2023-04-16T16:20:21","modified_gmt":"2023-04-16T14:20:21","slug":"python-algorithme-de-seuil-pour-une-fonction","status":"publish","type":"page","link":"https:\/\/www.mathweb.fr\/euclide\/python-algorithme-de-seuil-pour-une-fonction\/","title":{"rendered":"Python : algorithme de seuil pour une fonction"},"content":{"rendered":"\n<p>\u00c9tant donn\u00e9e la fonction <em>f<\/em> d\u00e9finie pour tout r\u00e9el <em>x<\/em> par :$$f(x)=\\frac{x^2+3x+5}{x^2+1},$$ quelle est la premi\u00e8re valeur de <em>x<\/em> positive telle que \\(f(x)\\leqslant1.25\\) ? Pour r\u00e9pondre \u00e0 cette question, nous devons utiliser un <em>algorithme de seuil<\/em> pour fonction.<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"640\" src=\"https:\/\/www.mathweb.fr\/euclide\/wp-content\/uploads\/2020\/06\/Python-suite-algorithme-seuil-1024x640.png\" alt=\"Algorithme de seuil sur les fonctions\" class=\"wp-image-2560\" srcset=\"https:\/\/www.mathweb.fr\/euclide\/wp-content\/uploads\/2020\/06\/Python-suite-algorithme-seuil-1024x640.png 1024w, https:\/\/www.mathweb.fr\/euclide\/wp-content\/uploads\/2020\/06\/Python-suite-algorithme-seuil-300x188.png 300w, https:\/\/www.mathweb.fr\/euclide\/wp-content\/uploads\/2020\/06\/Python-suite-algorithme-seuil-600x375.png 600w, https:\/\/www.mathweb.fr\/euclide\/wp-content\/uploads\/2020\/06\/Python-suite-algorithme-seuil-768x480.png 768w, https:\/\/www.mathweb.fr\/euclide\/wp-content\/uploads\/2020\/06\/Python-suite-algorithme-seuil.png 1080w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption>Algorithme de seuil sur les fonctions<\/figcaption><\/figure><\/div>\n\n\n\n<figure class=\"wp-block-embed is-type-wp-embed is-provider-mathweb-fr wp-block-embed-mathweb-fr\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/www.mathweb.fr\/euclide\/produit\/python-en-mathematiques-au-lycee\/\n<\/div><\/figure>\n\n\n\n<p>Nous pouvons r\u00e9pondre \u00e0 cette question \u00e0 l&#8217;aide du programme Python suivant:<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"python\" data-enlighter-theme=\"dracula\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">def f(x):\n    return (x*x + 3*x + 5) \/ (x*x + 1)\n\nx = 0\nwhile f(x) >= 1.25:\n    x = x + 0.001\n    \nprint(\"\u00c0 partir de {}, f(x) est inf\u00e9rieur \u00e0 1.5.\".format(x))<\/pre>\n\n\n\n<p>La valeur 13.141999999998156 est affich\u00e9e (ce qui signifie une valeur de 13.142).<\/p>\n\n\n\n<p class=\"has-very-light-gray-color has-luminous-vivid-orange-background-color has-text-color has-background\">Quand on cherche la premi\u00e8re valeur de <em>x<\/em> pour que <em>f<\/em>(<em>x<\/em>) soit sup\u00e9rieure ou inf\u00e9rieure \u00e0 un nombre, on utilise une <em>boucle conditionnelle<\/em> &#8220;while&#8221;. La condition \u00e0 mettre est alors toujours la condition contraire de ce que l&#8217;on souhaite.<\/p>\n\n\n\n<p>On voulait la premi\u00e8re valeur de <em>x<\/em> pour que <em>f<\/em>(<em>x<\/em>) soit INFERIEURE OU EGALE \u00e0 1.25, donc la condition de la boucle &#8220;while&#8221; est : &#8220;<em>f<\/em>(<em>x<\/em>) SUPERIEURE \u00e0 1.25&#8243;.<\/p>\n\n\n\n<p>N&#8217;oubliez pas que si vous avez besoin d&#8217;un cours de maths par webcam, <a rel=\"noreferrer noopener\" href=\"https:\/\/courspasquet.fr\" target=\"_blank\">vous pouvez r\u00e9server sur ce site<\/a>.<\/p>\n\n\n\n<p><a href=\"https:\/\/www.mathweb.fr\/euclide\/ressources-python\/\">[Retour \u00e0 la page principale]<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u00c9tant donn\u00e9e la fonction f d\u00e9finie pour tout r\u00e9el x par :$$f(x)=\\frac{x^2+3x+5}{x^2+1},$$ quelle est la premi\u00e8re valeur de x positive telle que \\(f(x)\\leqslant1.25\\) ? Pour r\u00e9pondre \u00e0 cette question, nous devons utiliser un algorithme de seuil pour fonction. Nous pouvons r\u00e9pondre \u00e0 cette question \u00e0 l&#8217;aide du programme Python suivant: [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-2354","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Python : algorithme de seuil pour une fonction - Mathweb.fr<\/title>\n<meta name=\"description\" content=\"Sur cette page, un algorithme de seuil appliqu\u00e9 \u00e0 une fonction est donn\u00e9. 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