import os
USE_SYMENGINE = os.getenv('USE_SYMENGINE', '0')
USE_SYMENGINE = USE_SYMENGINE.lower() in ('1', 't', 'true')

if USE_SYMENGINE:
    from symengine import (Symbol, Integer, sympify, S,
        SympifyError, exp, log, gamma, sqrt, I, E, pi, Matrix,
        sin, cos, tan, cot, csc, sec, asin, acos, atan, acot, acsc, asec,
        sinh, cosh, tanh, coth, asinh, acosh, atanh, acoth,
        lambdify, symarray, diff, zeros, eye, diag, ones, zeros,
        expand, Function, symbols, var, Add, Mul, Derivative,
        ImmutableMatrix, MatrixBase, Rational, Basic)
    from symengine.lib.symengine_wrapper import gcd as igcd
    from symengine import AppliedUndef
else:
    from sympy import (Symbol, Integer, sympify, S,
        SympifyError, exp, log, gamma, sqrt, I, E, pi, Matrix,
        sin, cos, tan, cot, csc, sec, asin, acos, atan, acot, acsc, asec,
        sinh, cosh, tanh, coth, asinh, acosh, atanh, acoth,
        lambdify, symarray, diff, zeros, eye, diag, ones, zeros,
        expand, Function, symbols, var, Add, Mul, Derivative,
        ImmutableMatrix, MatrixBase, Rational, Basic, igcd)
    from sympy.core.function import AppliedUndef