>>>import math      #导入math模块

>>>dir(math)        #这句可查看所有函数名列表

>>>help(math)       #查看具体定义及函数原型

acos(x)       # Return the arc cosine (measured in radians) of x.

asin(x)       # Return the arc sine (measured in radians) of x.

atan(x)       # Return the arc tangent (measured in radians) of x.

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.

ceil(x)       # Return the ceiling of x as a float.

              # This is the smallest integral value >= x.

cos(x)        # Return the cosine of x (measured in radians).

cosh(x)       # Return the hyperbolic(双曲线的) cosine of x.

degrees(x)    # converts angle x from radians(弧度) to degrees

exp(x)        # Return e raised to the power of x.

fabs(x)       # Return the absolute value of the float x.

floor(x)      # Return the floor of x as a float.

              # This is the largest integral value <= x.

fmod(x,y)     # Return fmod(x, y), according to platform C.  x % y may differ.

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.

hypot(x,y)    # Return the Euclidean distance, sqrt(x*x + y*y).

ldexp(x, i)   # x * (2**i)

log(x[, base])   # the logarithm of x to the given base.

                 # If the base not specified, returns the natural logarithm (base e) of x.

log10(x)      # the base 10 logarithm of x.

modf(x)       # Return the fractional and integer parts of x.  Both results carry the sign

              # of x.  The integer part is returned as a real.

pow(x,y)      # Return x**y (x to the power of y).

radians(x)    # converts angle x from degrees to radians

sin(x)        # Return the sine of x (measured in radians).

sinh(x)       # Return the hyperbolic sine of x.

sqrt(x)       # Return the square root of x.

tan(x)        # Return the tangent of x (measured in radians).

tanh(x)       # Return the hyperbolic tangent of x.

e  = 2.7182818284590451

pi = 3.1415926535897931