# Home

## 15. Guyou map projection

## `sasmodels.guyou`

Convert between latitude-longitude and Guyou map coordinates.

sasmodels.guyou.ellipticFi(phi, psi, m)

  Returns F(phi+ipsi|m). See Abramowitz and Stegun, 17.4.11.

sasmodels.guyou.ellipticJi(u, v, m)

  Returns [sn, cn, dn](u + iv|m).

sasmodels.guyou.guyou(lam, phi)

  Transform from (latitude, longitude) to point (x, y)

sasmodels.guyou.guyou_invert(x, y)

  Transform from point (x, y) on plot to (latitude, longitude)

sasmodels.guyou.main()

  Show the Guyou transformation

sasmodels.guyou.plot_grid()

  Plot the latitude-longitude grid for Guyou transform