code: def rho_matrix(sh_order, vecs):
      r"""Compute the SH matrix $\rho$"""
  
      r, theta, phi = cart2sphere(vecs[:, 0], vecs[:, 1], vecs[:, 2])
      theta[np.isnan(theta)] = 0
  
      n_c = int((sh_order + 1) * (sh_order + 2) / 2)
      rho = np.zeros((vecs.shape[0], n_c))
      counter = 0
      for l in range(0, sh_order + 1, 2):
          for m in range(-l, l + 1):
              rho[:, counter] = real_sh_descoteaux_from_index(
                  m, l, theta, phi
              )
              counter += 1
      return rho
  
imports: from warnings import warn
  import numpy
  from dipy.reconst.cache import Cache
  from dipy.reconst.multi_voxel import multi_voxel_fit
  from dipy.reconst.csdeconv import csdeconv
  from dipy.reconst.shm import real_sh_descoteaux_from_index
  from scipy.special import gamma, hyp1f1
  from dipy.core.geometry import cart2sphere
  from dipy.data import default_sphere
  from dipy.reconst.odf import OdfModel, OdfFit
  from scipy.optimize import leastsq
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 5 for calling a global function with example usage: rho_matrix(sh_order, vecs) and returns: rho