Importation d’un module intégré (builtin)
Nous importons le module « math » qui est intégré au langage et qui va nous permettre de réaliser des opérations mathématiques simples
>>> import math >>> print (math.pi) 3.141592653589793 >>> math.sqrt (16) 4.0 >>>
Avec la fonction intégrée help ( ), nous pouvons demander de l’aide et faire appel à la documentation du module
>>> help ("math.sqrt") Help on built-in function sqrt in math: math.sqrt = sqrt(...) sqrt(x) Return the square root of x. >>>
La fonction math.sqrt ( ) renvoie donc la raciné carrée du nombre mis entre parenthèses.
Mais d’où vient cette valeur de pi ? Consultons l’aide générale du module math :
>>> help ("math") Help on built-in module math: NAME math DESCRIPTION This module is always available. It provides access to the mathematical functions defined by the C standard. FUNCTIONS acos(...) acos(x) Return the arc cosine (measured in radians) of x. acosh(...) acosh(x) Return the inverse hyperbolic cosine of x. asin(...) asin(x) Return the arc sine (measured in radians) of x. asinh(...) asinh(x) Return the inverse hyperbolic sine of x. atan(...) atan(x) Return the arc tangent (measured in radians) of x. atan2(...) atan2(y, x) Return the arc tangent (measured in radians) of y/x. Unlike atan(y/x), the signs of both x and y are considered. atanh(...) atanh(x) Return the inverse hyperbolic tangent of x. ceil(...) ceil(x) Return the ceiling of x as an int. This is the smallest integral value >= x. copysign(...) copysign(x, y) Return a float with the magnitude (absolute value) of x but the sign of y. On platforms that support signed zeros, copysign(1.0, -0.0) returns -1.0. cos(...) cos(x) Return the cosine of x (measured in radians). cosh(...) cosh(x) Return the hyperbolic cosine of x. degrees(...) degrees(x) Convert angle x from radians to degrees. erf(...) erf(x) Error function at x. erfc(...) erfc(x) Complementary error function at x. exp(...) exp(x) Return e raised to the power of x. expm1(...) expm1(x) Return exp(x)-1. This function avoids the loss of precision involved in the direct evaluation of exp(x)-1 for small x. fabs(...) fabs(x) Return the absolute value of the float x. factorial(...) factorial(x) -> Integral Find x!. Raise a ValueError if x is negative or non-integral. floor(...) floor(x) Return the floor of x as an int. This is the largest integral value <= x. fmod(...) fmod(x, y) Return fmod(x, y), according to platform C. x % y may differ. frexp(...) frexp(x) Return the mantissa and exponent of x, as pair (m, e). m is a float and e is an int, such that x = m * 2.**e. If x is 0, m and e are both 0. Else 0.5 <= abs(m) < 1.0. fsum(...) fsum(iterable) Return an accurate floating point sum of values in the iterable. Assumes IEEE-754 floating point arithmetic. gamma(...) gamma(x) Gamma function at x. hypot(...) hypot(x, y) Return the Euclidean distance, sqrt(x*x + y*y). isfinite(...) isfinite(x) -> bool Return True if x is neither an infinity nor a NaN, and False otherwise. isinf(...) isinf(x) -> bool Return True if x is a positive or negative infinity, and False otherwise. isnan(...) isnan(x) -> bool Return True if x is a NaN (not a number), and False otherwise. ldexp(...) ldexp(x, i) Return x * (2**i). lgamma(...) lgamma(x) Natural logarithm of absolute value of Gamma function at x. log(...) log(x[, base]) Return the logarithm of x to the given base. If the base not specified, returns the natural logarithm (base e) of x. log10(...) log10(x) Return the base 10 logarithm of x. log1p(...) log1p(x) Return the natural logarithm of 1+x (base e). The result is computed in a way which is accurate for x near zero. log2(...) log2(x) Return the base 2 logarithm of x. modf(...) modf(x) Return the fractional and integer parts of x. Both results carry the sign of x and are floats. pow(...) pow(x, y) Return x**y (x to the power of y). radians(...) radians(x) Convert angle x from degrees to radians. sin(...) sin(x) Return the sine of x (measured in radians). sinh(...) sinh(x) Return the hyperbolic sine of x. sqrt(...) sqrt(x) Return the square root of x. tan(...) tan(x) Return the tangent of x (measured in radians). tanh(...) tanh(x) Return the hyperbolic tangent of x. trunc(...) trunc(x:Real) -> Integral Truncates x to the nearest Integral toward 0. Uses the __trunc__ magic method. DATA e = 2.718281828459045 pi = 3.141592653589793 FILE (built-in) >>>
La valeur de pi est présente dans le module en tant que DATA ou données intégrées au module tout comme la valeur de e.
Plusieurs façons d’importer le module math et appeler la fonction sqrt ( ):
>>> import math >>> math.sqrt (64) 8.0 >>>
>>> from math import sqrt >>> sqrt (64) 8.0 >>>
>>> from math import * >>> sqrt (64) 8.0 >>>