Use max rho of surface to compute A(z)

[unalmis]

Resolves #1083

[github-actions]

|             benchmark_name             |         dt(%)          |         dt(s)          |        t_new(s)        |        t_old(s)        | 
| -------------------------------------- | ---------------------- | ---------------------- | ---------------------- | ---------------------- |
 test_build_transform_fft_lowres         |     +4.58 +/- 5.90     | +2.43e-02 +/- 3.13e-02 |  5.55e-01 +/- 2.9e-02  |  5.31e-01 +/- 1.1e-02  |
 test_build_transform_fft_midres         |     +3.20 +/- 2.43     | +1.98e-02 +/- 1.50e-02 |  6.36e-01 +/- 1.3e-02  |  6.16e-01 +/- 7.5e-03  |
 test_build_transform_fft_highres        |     +2.78 +/- 2.29     | +2.80e-02 +/- 2.31e-02 |  1.03e+00 +/- 1.8e-02  |  1.01e+00 +/- 1.4e-02  |
 test_equilibrium_init_lowres            |     +0.48 +/- 3.48     | +1.88e-02 +/- 1.37e-01 |  3.94e+00 +/- 1.2e-01  |  3.92e+00 +/- 5.7e-02  |
 test_equilibrium_init_medres            |     +0.66 +/- 4.66     | +2.90e-02 +/- 2.04e-01 |  4.40e+00 +/- 1.7e-01  |  4.37e+00 +/- 1.1e-01  |
 test_equilibrium_init_highres           |     -0.95 +/- 2.85     | -5.49e-02 +/- 1.65e-01 |  5.74e+00 +/- 1.1e-01  |  5.80e+00 +/- 1.2e-01  |
 test_objective_compile_dshape_current   |     -1.72 +/- 1.09     | -6.76e-02 +/- 4.28e-02 |  3.87e+00 +/- 3.1e-02  |  3.94e+00 +/- 2.9e-02  |
 test_objective_compile_atf              |     -0.62 +/- 2.36     | -5.23e-02 +/- 1.99e-01 |  8.37e+00 +/- 1.1e-01  |  8.42e+00 +/- 1.7e-01  |
 test_objective_compute_dshape_current   |     -2.34 +/- 5.45     | -3.01e-05 +/- 7.02e-05 |  1.26e-03 +/- 3.5e-05  |  1.29e-03 +/- 6.1e-05  |
 test_objective_compute_atf              |     -0.11 +/- 5.62     | -4.64e-06 +/- 2.40e-04 |  4.27e-03 +/- 1.6e-04  |  4.28e-03 +/- 1.8e-04  |
 test_objective_jac_dshape_current       |     -8.02 +/- 9.78     | -3.12e-03 +/- 3.80e-03 |  3.58e-02 +/- 1.8e-03  |  3.89e-02 +/- 3.3e-03  |
 test_objective_jac_atf                  |     -1.66 +/- 3.45     | -3.16e-02 +/- 6.57e-02 |  1.87e+00 +/- 5.9e-02  |  1.90e+00 +/- 2.8e-02  |
 test_perturb_1                          |     -1.60 +/- 2.91     | -2.19e-01 +/- 3.98e-01 |  1.35e+01 +/- 3.2e-01  |  1.37e+01 +/- 2.3e-01  |
 test_perturb_2                          |     -2.89 +/- 2.77     | -5.56e-01 +/- 5.33e-01 |  1.87e+01 +/- 3.0e-01  |  1.93e+01 +/- 4.4e-01  |
 test_proximal_jac_atf                   |     -1.04 +/- 1.84     | -7.71e-02 +/- 1.36e-01 |  7.33e+00 +/- 8.2e-02  |  7.40e+00 +/- 1.1e-01  |
-test_proximal_freeb_compute             |    +20.75 +/- 1.04     | +3.75e-02 +/- 1.88e-03 |  2.18e-01 +/- 1.2e-03  |  1.81e-01 +/- 1.4e-03  |
+test_proximal_freeb_jac                 |     -9.03 +/- 0.85     | -7.37e-01 +/- 6.90e-02 |  7.42e+00 +/- 6.2e-02  |  8.16e+00 +/- 3.1e-02  |
 test_solve_fixed_iter                   |     -0.03 +/- 10.87    | -4.45e-03 +/- 1.64e+00 |  1.51e+01 +/- 1.2e+00  |  1.51e+01 +/- 1.1e+00  |

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.98%. Comparing base (4745460) to head (5c3d5f0).
Report is 2131 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1086   +/-   ##
=======================================
  Coverage   94.98%   94.98%           
=======================================
  Files          87       87           
  Lines       21743    21748    +5     
=======================================
+ Hits        20652    20657    +5     
  Misses       1091     1091           

Files with missing lines	Coverage Δ
desc/compute/_basis_vectors.py	87.11% <100.00%> (+0.10%)	⬆️
desc/compute/_geometry.py	82.78% <100.00%> (+0.07%)	⬆️

... and 2 files with indirect coverage changes