Python: unexplained discrepancy in calculations with other languages

[cosinekitty]

The other language pairs tested by generate/diffcalc all agree with each other within about 6.0e-15. However, Python suddenly lost precision. For now I'm going to patch diffcalc to have a larger error tolerance, but this needs to be investigated and fixed.

First  file: temp/c_check.txt
Second file: temp/py_check.txt
Tolerance = 4.000e-12

            lnum                 a_value                 b_value     factor       diff  name
  OK       22073  2.4668955106186205e-01  2.4668955106091364e-01    3.25733  3.089e-12  helio_x
  OK        5166  1.1953727682351487e-02  1.1953727681402368e-02    3.25733  3.092e-12  helio_y
  OK        5166  4.6053567996951844e-02  4.6053567996540354e-02    3.25733  1.340e-12  helio_z
  OK       81758  4.7416398275054599e+00  4.7416398274975968e+00    0.01730  1.360e-13  sky_j2000_ra
  OK      522326 -2.9618752903733236e-01 -2.9618752899582923e-01    0.00556  2.306e-13  sky_j2000_dec
  OK        5952  6.0769706688656411e-01  6.0769706688737724e-01    3.54610  2.883e-12  sky_j2000_dist
  OK       54701  3.4252017097808329e+02  3.4252017097859942e+02    0.00275  1.422e-12  sky_hor_az
  OK        7489 -4.9974625864690580e+01 -4.9974625864819728e+01    0.00556  7.175e-13  sky_hor_alt
  OK        2085  3.9813854037812494e-03  3.9813854037812502e-03  223.21429  1.936e-16  jm_x
  OK       61071 -2.2351447277631164e-03 -2.2351447277631155e-03  223.21429  1.936e-16  jm_y
  OK       61071 -1.1075179242594577e-03 -1.1075179242594573e-03  223.21429  9.680e-17  jm_z
  OK      243394 -7.1148311390774070e-03 -7.1148311390774087e-03  126.58228  2.196e-16  jm_vx
  OK       96772  3.0202250049769577e-03  3.0202250049769586e-03  212.76596  1.845e-16  jm_vy
  OK       15627  3.5037044145441172e-03  3.5037044145441181e-03  100.00000  8.674e-17  jm_vz
  OK        2871 -1.5575664421775793e+01 -1.5575664421775796e+01    0.10000  3.553e-16  psi
  OK      104284  5.5823579796157814e+00  5.5823579796157796e+00    0.10000  1.776e-16  eps
  OK      234263  4.3622390731197669e+00  4.3622390731197607e+00    0.00556  3.454e-17  moon_lat
  OK      447848  2.9698680233665476e+02  2.9698680233665470e+02    0.00275  1.564e-16  moon_lon
  OK      235220  2.6472641919042627e-03  2.6472641919042619e-03  333.33333  2.891e-16  moon_dist

Score = 3.092e-12