[junmaoy]

'Dx=-0.3*pi*sin(2*pi*t)*cos(x)/sin(y)/z',
'Dy=0.3*pi*sin(2*pi*t)*(cos(x)-sin(x)*sin(y)*z)/(sin(y)*z^2)-0.3*pi*cos(2*pi*t)*sin(y)/z',
'Dz=0.3*pi*sin(2*pi*t)*(cos(x)-sin(x)*sin(y)*z)/z+0.3*pi*cos(2*pi*t)*cos(y)','x(0)=0,y(0)=0,z(0)=0.5'
x,y,z都是t的函数