• # Et Yacas ?

    Posté par . En réponse au journal Calcul formel. Évalué à 3.

    Salut skyppy,

    J'utilise depuis des années une petite merveille de logiciel appellé yacas.
    Si tu utilise les casio graph 100 en mode calcul formel, ca y ressemble très fort.

    Voici le site: http://www.xs4all.nl/~apinkus/yacas.html(...)

    Yacas veut dire 'Yet another Computer Algebra System'
    Je pense que ce programme mérite vraiment que l'on s'y interesse, il en vaut vraiment vraiment la peine ... bon assez parlé, regardez les exemples d'utilisation ci dessous:


    [~]$ yacas
    [unix.ys] [editvi.ys]
    True;
    This is Yacas version '1.0.56'.
    Yacas is Free Software--Free as in Freedom--so you can redistribute Yacas or
    modify it under certain conditions. Yacas comes with ABSOLUTELY NO WARRANTY.
    See the GNU General Public License (GPL) for the full conditions.
    Type ?license or ?licence to see the GPL; type ?warranty for warranty info.
    See http://yacas.sf.net(...) for more information and documentation on Yacas.

    Numeric mode: "Internal"
    To exit Yacas, enter Exit(); or quit or Ctrl-c. Type ?? for help.
    Or type ?function for help on a function.
    Type 'restart' to restart Yacas.
    To see example commands, keep typing Example();
    In> Example();
    Current example : 40!;

    Simple factorial of a number.

    Out> 815915283247897734345611269596115894272000000000
    In> Example();
    Current example : D(x)Sin(x);

    Taking the derivative of a function (the derivative of Sin(x) with
    respect to x in this case).

    Out> Cos(x)
    In> Example();
    Current example : Taylor(x,0,5)Sin(x);

    Expanding a function into a taylor series.

    Out> x-x^3/6+x^5/120
    In> Example();
    Current example : Integrate(x,a,b)Sin(x);

    Integrate a function.

    Out> Cos(a)-Cos(b)
    In> Example();
    Current example : Solve(a+x*y==z,x);

    Solve a function for a variable.

    Out> {x== -(a-z)/y}
    In> Example();
    Current example : Limit(x,0)Sin(x)/x;

    Take a limit.

    Out> 1
    In> Example();
    Current example : Subst(x,Cos(a))x+x;

    Substitute an expression with another in the main expression.

    Out> 2*Cos(a)
    In> Example();
    Current example : Expand((1+x)^3);

    Expand into a polynomial.

    Out> x^3+3*x^2+3*x+1
    In> Example();
    Current example : 2^40;

    Big numbers.

    Out> 1099511627776
    In> Example();
    Current example : 1<<40;

    Bitwise operations

    Out> 1099511627776
    In> Example();
    Current example : 1..4;

    Generating a list of numbers.

    Out> {1,2,3,4}
    In> Example();
    Current example : a:b:c:{};

    Generating a list of items.

    Out> {a,b,c}
    In> Example();
    Current example : [Local(x);x:={a,b,c};Sin(x)^2;];

    Threading: Sin(..)^2 will be performed on all elements of the list
    passed in.

    Out> {Sin(a)^2,Sin(b)^2,Sin(c)^2}
    In> Example();
    Current example : [Local(list);list:={a,b,c,d,e,f};list[2..4];];

    Selecting a sublist from a list.

    Out> {b,c,d}
    In> Example();
    Current example : Permutations({a,b,c});

    Generate all permutations of a list.

    Out> {{a,b,c},{a,c,b},{c,a,b},{b,a,c},{b,c,a},{c,b,a}}
    In> Example();
    Current example : VarList(a+b*x);

    Show all variables that occur in an expression.

    Out> {a,b,x}
    In> Example();
    Current example : TrigSimpCombine(Cos(a)*Cos(a)+Sin(a)*Sin(a));

    Convert factors between trigonometric functions to addition of
    trigonometric functions.

    Out> 1
    In> Taylor(x,0,3) Exp(x)
    Out> x+x^2/2+x^3/6+1
    In> PrettyForm(%);

    2 3
    x x
    x + -- + -- + 1
    2 6

    Out> True


    La dernière fonction est particulièrement interessante, vous ne trouvez pas ? :)

    Alors qu'en pensez vous ?