302.sagews

# Mathematical Physics 
# http://www1.uprh.edu/rbaretti/
#http://www1.uprh.edu/rbaretti/methodsoftheoreticalphysics.htm
#http://www1.uprh.edu/rbaretti/methodsoftheoreticalphysicsPart2.htm
#http://www1.uprh.edu/rbaretti/methodsoftheoreticalphysicsPart3.htm
#http://www1.uprh.edu/rbaretti/methodsoftheoreticalphysicsPart4.htm 
#http://www1.uprh.edu/rbaretti/methodsoftheoreticalphysicsPart5.htm 

 
 
i1,i2=var('i1,i2')
solve([200*i1-100*i2==1.5,-100*i1+200*i2==5],i1,i2)

[[i1 == 2/75, i2 == 23/600]]

R=RealField(20)
R(2/75)

0.026667

var('x')
f=(1+x^2)
integral(f,x,0,3)

12

R=RealField(30)
x=11/23
R(x)

0.47826087

i1,i2,i3=var('i1,i2,i3')
solve([-7*i1+i2+0*i3==-10,i1-5*i2+3*i3==0,0*i1+3*i2-13*i3==20],i1,i2,i3)

[[i1 == 500/379, i2 == -290/379, i3 == -650/379]]

R=RealField(30)
R(500/379) ; R(-290/379);R(-650/379);

1.3192612 -0.76517150 -1.7150396