Thanks! I did not know about nsolve.
Would nsolve be ‚better‘ than converting the equations to numpy, using
lambdify, and the use scipy.optimize.fsolve ?
Thanks, Peter
On Fri 23. Sep 2022 at 20:18 Aaron Meurer <asmeu...@gmail.com> wrote:
> If you are only interested in a numerical solution, you are better off
> using nsolve(). solve() only tries to find a closed-form symbolic
> solution, and the solution to this system might not even exist in
> closed-form.
>
> For example:
>
> >>> nsolve([eq1,eq2,eq3], [x, y, z], [1j, 1j, 1j])
> Matrix([
> [0.785398163397448 - 7.44899462227771e-31*I],
> [ 0.0356339138701676 + 0.615283513362025*I],
> [-6.32074851537401e-24 + 1.23056702672405*I]])
>
> Small values can be trimmed to 0 with chop:
>
> >>> _.evalf(chop=True)
> Matrix([
> [ 0.785398163397448],
> [0.0356339138701676 + 0.615283513362025*I],
> [ 1.23056702672405*I]])
>
> Here I used a complex starting point since the solution is complex,
> and nsolve() typically won't find complex solutions unless the
> starting point is complex.
>
> Aaron Meurer
>
> On Thu, Sep 22, 2022 at 10:59 AM Jean Marc Roberge
> <jmroberg...@gmail.com> wrote:
> >
> > I am trying to solve 3 trigonometric equation using the solve operation
> in simply but program never exits loop. per the code below I first
> calculate the result of the equation using known values (x1,y1,z1) and then
> use the result of that to as the answer in the equation to solve. the
> answer should be the x1,z1,z1 values initially used but the loop never ends
> and provides no result.
> > What as I doing incorrectly ?
> >
> > code used
> > import sympy as sym
> > from sympy import solve, Eq
> > from sympy import sin,cos
> > rad=.01745329
> > x1=30*rad
> > y1=15*rad
> > z1=25*rad
> > l1=50.00
> > l2=50.00
> > l3=50.00
> > x,y,z= sym.symbols("x,y,z")
> >
> > print((l2*cos(y1)+l3*cos(z1-y1))*cos(x1))
> > print((l2*cos(y1)+l3*cos(z1-y1))*sin(x1))
> > print(l1+(l2*sin(y1)-l3*sin(z1-y1)))
> >
> > eq1 = Eq((l2*cos(y)+l3*cos(z-y))*cos(x),84.4692460844174)
> > eq2 = Eq((l2*cos(y)+l3*cos(z-y))*sin(x),84.4692460844174)
> > eq3 = Eq((l1+(l2*sin(y)-l3*sin(z-y))),54.2585427870506)
> >
> > result = solve([eq1,eq2,eq3],[x,y,z])
> > print(result)
> >
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Best regards,
Peter Stahlecker
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