watex.externals.zutils.propagate_error_polar2rect

watex.externals.zutils.propagate_error_polar2rect(r, r_error, phi, phi_error)

Find error estimations for the transformation from polar to cartesian coordinates.

Uncertainties in polar representation define a section of an annulus. Find the 4 corners of this section and additionally the outer boundary point, which is defined by phi = phi0, rho = rho0 + sigma rho. The cartesian “box” defining the uncertainties in x,y is the outer bound around the annulus section, defined by the four outermost points. So check the four corners as well as the outer boundary edge of the section to find the extrema in x znd y. These give you the sigma_x/y.