code: def _calc_detlam(xx, yy, zz, yx, zx, zy):
      """
      Calculate determinant of symmetric 3x3 matrix
  
      [[xx,yx,xz],
       [yx,yy,zy],
       [zx,zy,zz]]
      """
  
      return (
          zz * (yy * xx - yx**2)
          - zy * (zy * xx - zx * yx)
          + zx * (zy * yx - zx * yy)
      )
  
file_path: nipy/nipy/algorithms/fwhm.py
imports: import numpy
  from numpy.linalg import det
  from nipy.core.api import Image
  from .utils.matrices import pos_recipr
label_desc: Use image node_id 1 for calling a global function with example usage: _calc_detlam(xx, yy, zz, yx, zx, zy) and returns: unknown