coxeter3 Package installed, but cannot use it

[zhang...@gmail.com]

Platform: Mac 

Version: 8.1

I installed the package coxeter3 using 

!sage -i coxeter3

and it was successfully installed.

But I run a code using this package, I got 

RunrimeError:coxeter3 must be installed

Here is my code:

def MuL(C):

    W = CoxeterGroup(C, implementation='coxeter3')

    List=[]

    for u in W:

        U = (W(v) for v in W.bruhat_interval(u, W.long_element()))

        next(U)

        for v in U:

            ld = v.length()-u.length()-1

            if is_even(ld):

                p = W.kazhdan_lusztig_polynomial(u, v)

                if p[ld//2] != 0:

                    List += [[u,v]]

    return List

(ref: http://www.findstat.org/StatisticsDatabase/St001143)

Here is a demo:

MuL(CartanType(["A",5]))

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-17-c1a05b610d54> in <module>()
----> 1 MuL(CartanType(["A",Integer(5)]))

<ipython-input-16-71a5a95492cf> in MuL(C)
      1 def MuL(C):
----> 2     W = CoxeterGroup(C, implementation='coxeter3')
      3     List=[]
      4     for u in W:
      5         U = (W(v) for v in W.bruhat_interval(u, W.long_element()))

/Applications/SageMath-8.1.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/combinat/root_system/coxeter_group.pyc in CoxeterGroup(data, implementation, base_ring, index_set)
    141             from sage.libs.coxeter3.coxeter_group import CoxeterGroup
    142         except ImportError:
--> 143             raise RuntimeError("coxeter3 must be installed")
    144         else:
    145             return CoxeterGroup(cartan_type)

RuntimeError: coxeter3 must be installed

I then tried 

!sage -f coxeter3

to reinstall it, but the same error occurs. For more details of how I installed it, see the attached html file.

What is the problem with this and how to resolve it?

Thankyou!

[John H Palmieri]

After installing coxeter, did you run `./sage -b`? This might be necessary to rebuild the parts of the Sage library that use coxeter.