sympy

###   符号运算


from sympy import *


# code_01


#x = Symbol('x')  
#y = Symbol('y')  
#print(solve([2*x-y-3,3*x+y-7],[x,y]))






# code_02


#n = Symbol('n')  
#s = ((n+3)/(n+2))**n  
#print(limit(s,n,oo))


#code_03


#t,x=symbols('t x')
#m=integrate(sin(t)/(pi-t),(t,0,x))
#n=integrate(m,(x,0,pi))
#print(n)


#code_04


#from sympy import *
#x1,x2,x3 = symbols('x1 x2 x3')
#a11,a12,a13,a22,a23,a33 = symbols('a11 a12 a13 a22 a23 a33')
#m = Matrix([[x1,x2,x3]])
#n = Matrix([[a11,a12,a13],[a12,a22,a23],[a13,a23,a33]])
#v = Matrix([[x1],[x2],[x3]])
#f = m * n * v
#print (f[0])
#print('\n')
#print (f[0].subs({x1:1, x2:1, x3:1}))