{"id":170,"date":"2008-05-31T18:17:52","date_gmt":"2008-05-31T16:17:52","guid":{"rendered":"http:\/\/wordpress.callac.online\/index.php\/expression-ou-fonction-avec-xcas\/"},"modified":"2023-10-14T20:13:48","modified_gmt":"2023-10-14T18:13:48","slug":"expression-ou-fonction-avec-xcas","status":"publish","type":"page","link":"https:\/\/wordpress.callac.online\/index.php\/logiciels-mathematiques\/xcas\/fonctions-avec-xcas\/expression-ou-fonction-avec-xcas\/","title":{"rendered":"Expression ou fonction avec Xcas ?"},"content":{"rendered":"

\nDans Xcas, pour faire du calcul formel, on a la possibilit\u00e9 d’utiliser des expressions ou des fonctions.<\/p>\n

Je vais essayer de pr\u00e9senter ici les diff\u00e9rences entre elles.<\/p>\n

Les expressions<\/h2>\n
\n

C’est la mati\u00e8re premi\u00e8re pour faire du calcul formel avec Xcas, m\u00eame lorsqu’on veut d\u00e9crire une fonction math\u00e9matique.<\/p>\n

Ainsi, pour rentrer la fonction $f$ d\u00e9finie par $f(x)=\\left(x-3\\right)^2<\/em>-(x+3)(2x-1)$, on tape :<\/p>\n

\n\nf:=(x-3)^2-(x+3)*(2x-1)\n<\/code>\n<\/font color><\/p>\n

$$\\left(x-3\\right)^2<\/em>-(x+3)(2x-1)$$<\/p>\n

On obtient alors l’expression f<\/strong>, tr\u00e8s adapt\u00e9e au calcul formel.<\/p>\n

Voici quelques utilisations possibles.<\/p>\n

\n\nsimplifier(f)\n<\/code>\n<\/font color><\/p>\n

$$-x^2<\/em>-11x+12$$<\/p>\n

\n\nfactoriser(f)\n<\/code>\n<\/font color><\/p>\n

$$-(x+12)(x-1)$$<\/p>\n

\n\nresoudre(f=0,x)\n<\/code>\n<\/font color><\/p>\n

$$[-12,1]$$<\/p>\n

\n\nsimplifier(deriver(f,x))\n<\/code>\n<\/font color><\/p>\n

$$-2x-11$$<\/p>\n

A noter que ce r\u00e9sultat est lui aussi une expression, non une fonction.<\/p>\n

\n\nplotfunc(f,x=-15..5)\n<\/code>\n<\/font color><\/p>\n

\"courbe.jpg\"<\/p>\n

Cependant, \u00e0 ce stade, on ne peut pas calculer $f(2)$ par exemple, car f<\/strong> est une expression et non une fonction!<\/p>\n

De l’expression \u00e0 la fonction<\/h2>\n
\n

\n\nff:=unapply(f,x)\n<\/code>\n<\/font color><\/p>\n

$$x-> \\left(x-3\\right)^2<\/em>-(x+3)(2x-1)$$<\/p>\n

\n\nff(2)\n<\/code>\n<\/font color><\/p>\n

$$-14$$<\/p>\n

<\/math><\/p>\n","protected":false},"excerpt":{"rendered":"

Dans Xcas, pour faire du calcul formel, on a la possibilit\u00e9 d’utiliser des expressions ou des fonctions. Je vais essayer de pr\u00e9senter ici les diff\u00e9rences entre elles. Les expressions C’est…<\/p>\n","protected":false},"author":1,"featured_media":676,"parent":2226,"menu_order":1,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-170","page","type-page","status-publish","has-post-thumbnail","hentry"],"yoast_head":"\nExpression ou fonction avec Xcas ? - Maths & Num\u00e9rique<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/wordpress.callac.online\/index.php\/logiciels-mathematiques\/xcas\/fonctions-avec-xcas\/expression-ou-fonction-avec-xcas\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Expression ou fonction avec Xcas ? - Maths & Num\u00e9rique\" \/>\n<meta property=\"og:description\" content=\"Dans Xcas, pour faire du calcul formel, on a la possibilit\u00e9 d’utiliser des expressions ou des fonctions. 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