DimensionalityError when trying to use solution array as initial guess for SP solve

Less of an issue, and more of a question on the new corrected syntax. 2 different causes of DimensionalityError:

---------------------------------------------------------------------------
DimensionalityError                       Traceback (most recent call last)
/Users/philippekirschen/Documents/MIT/Research/GPjet/gpjet/vtail/vtail.py in <module>()
    175 
    176 if __name__ == "__main__":
--> 177     VerticalTail().test()

/Users/philippekirschen/Documents/MIT/Research/GPjet/gpjet/vtail/vtail.py in test(self)
    151 
    152         npt.assert_almost_equal(sol('\\Delta x_{trail}'), sol('c_{root}')
--> 153                                 + sol('\\Delta x_{lead}'), decimal=4)
    154         npt.assert_almost_equal(sol('\\Delta x_{lead}') + sol('z_{\\bar{c}}')
    155                                 *sol('\\tan(\\Lambda_{LE})')

/Users/philippekirschen/anaconda/lib/python2.7/site-packages/numpy/testing/utils.pyc in assert_almost_equal(actual, desired, decimal, err_msg, verbose)
    487     except (NotImplementedError, TypeError):
    488         pass
--> 489     if round(abs(desired - actual), decimal) != 0 :
    490         raise AssertionError(_build_err_msg())
    491 

/Users/philippekirschen/anaconda/lib/python2.7/site-packages/pint/quantity.pyc in __float__(self)
    280         if self.dimensionless:
    281             return float(self._convert_magnitude_not_inplace(UnitsContainer()))
--> 282         raise DimensionalityError(self.units, 'dimensionless')
    283 
    284     def __complex__(self):

DimensionalityError: Cannot convert from 'meter' to 'dimensionless'

[philippekirschen@dhcp-18-189-101-248 aircraft]$ ipython aircraft.py
Beginning signomial solve.
The 'setup' method of this model had an error.
---------------------------------------------------------------------------
DimensionalityError                       Traceback (most recent call last)
/Users/philippekirschen/Documents/MIT/Research/GPjet/gpjet/aircraft/aircraft.py in <module>()
     86 
     87 if __name__ == "__main__":
---> 88     Aircraft()#.test()
     89 

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/model.pyc in __init__(self, cost, constraints, substitutions, *args, **kwargs)
     84                 extended_args.extend(args)
     85                 name = kwargs.pop("name", self.__class__.__name__)
---> 86                 setup = self.setup(*extended_args, **kwargs)
     87             except:
     88                 print("The 'setup' method of this model had an error.")

/Users/philippekirschen/Documents/MIT/Research/GPjet/gpjet/aircraft/aircraft.py in setup(self)
     78                    init2[newkey] = value
     79 
---> 80             aircraft.localsolve(x0=init2)
     81 
     82         return aircraft

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/model.pyc in localsolve(self, solver, verbosity, skipsweepfailures, *args, **kwargs)
    383             with SignomialsEnabled():
    384                 return self._solve("sp", solver, verbosity, skipsweepfailures,
--> 385                                    *args, **kwargs)
    386         except ValueError as err:
    387             if err.message == ("SignomialPrograms must contain at least one"

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/model.pyc in _solve(self, programType, solver, verbosity, skipsweepfailures, *args, **kwargs)
    500             self.program, solvefn = form_program(programType, signomials,
    501                                                  verbosity=verbosity)
--> 502             result = solvefn(*args, **kwargs)
    503             solution.append(parse_result(result, constants, beforesubs))
    504         solution.program = self.program

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/signomial_program.py in localsolve(self, solver, verbosity, x0, rel_tol, iteration_limit, *args, **kwargs)
    115     appear to be converging, you may wish to increase the iteration limit by
    116     calling .localsolve(..., iteration_limit=NEWLIMIT).""" % len(self.gps))
--> 117             gp = self.step(x0, verbosity=verbosity-1)
    118             self.gps.append(gp)  # NOTE: SIDE EFFECTS
    119             try:

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/signomial_program.py in step(self, x0, verbosity)
    169                 posy_approx = p
    170             else:
--> 171                 posy_approx = p/n.mono_lower_bound(x0)
    172 #                posy_approxs.append(posy_approx)
    173 #                posy_approx = 1/posy_approx

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/nomials.pyc in mono_lower_bound(self, x_0)
    484         Monomial
    485         """
--> 486         return self.mono_approximation(x_0)
    487 
    488 

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/nomials.pyc in mono_approximation(self, x_0)
    172         x_0 = get_constants(self, x_0)
    173         exp = HashVector()
--> 174         psub = self.sub(x_0)
    175         if psub.varlocs:
    176             raise ValueError("Variables %s remained after substituting x_0=%s"

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/nomials.pyc in sub(self, substitutions, val, require_positive)
    206         Returns substituted nomial.
    207         """
--> 208         _, exps, cs, _ = substitution(self, substitutions, val)
    209         return Signomial(exps, cs, require_positive=require_positive)
    210 

/Users/philippekirschen/Documents/MIT/Research/GPkit/gpkit/gpkit/substitution.pyc in substitution(nomial, substitutions, val)
    158             if isinstance(sub, Numbers):
    159                 if sub != 0:
--> 160                     cs_[i] *= sub**x
    161                 else:  # frickin' pints bug. let's reimplement pow()
    162                     if x > 0:

/Users/philippekirschen/anaconda/lib/python2.7/site-packages/pint/quantity.pyc in __setitem__(self, key, value)
   1030                                               extra_msg='. Assign a quantity with the same dimensionality or '
   1031                                                         'access the magnitude directly as '
-> 1032                                                         '`obj.magnitude[%s] = %s`' % (key, value))
   1033                 self._magnitude[key] = factor.magnitude
   1034             else:

DimensionalityError: Cannot convert from '15253.5801059 newton ** 2' to 'newton'. Assign a quantity with the same dimensionality or access the magnitude directly as `obj.magnitude[2] = 15253.5801059 newton ** 2`

[pgkirsch]

I actually haven’t tested it with the second case, but when I do and if it works I will close.

[whoburg]

it works 😃