Add irftrn (#361)

* added 4 irf related functions

appveyor/cspice.def

@@ -261,6 +261,10 @@ EXPORTS			appndc_c
 				intmin_c
 				invert_c
 				invort_c
+				irfnam_
+				irfnum_
+				irfrot_
+				irftrn_
 				isordv_c
 				isrchc_c
 				isrchd_c

spiceypy/spiceypy.py

@@ -7444,6 +7444,84 @@ def invort(m: ndarray) -> ndarray:
     return stypes.c_matrix_to_numpy(mout)
 
 
+@spice_error_check
+def irfnam(index: int) -> str:
+    """
+    Return the name of one of the standard inertial reference
+    frames supported by :func:`irfrot`
+
+    https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/irfnam.html
+
+    :param index: Index of a standard inertial reference frame.
+    :return: is the name of the frame.
+    """
+    index = ctypes.c_int(index)
+    name = stypes.string_to_char_p(16)  # just give enough space
+    name_len = ctypes.c_int(16)
+    libspice.irfnam_(ctypes.byref(index), name, name_len)
+    return stypes.to_python_string(name)
+
+
+@spice_error_check
+def irfnum(name: str) -> int:
+    """
+    Return the index of one of the standard inertial reference
+    frames supported by :func:`irfrot`
+
+    https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/irfnum.html
+
+    :param name: Name of standard inertial reference frame.
+    :return: is the index of the frame.
+    """
+    index = ctypes.c_int()
+    name_len = ctypes.c_int(len(name))
+    name = stypes.string_to_char_p(name)
+    libspice.irfnum_(name, ctypes.byref(index), name_len)
+    return index.value
+
+
+@spice_error_check
+def irfrot(refa: int, refb: int) -> ndarray:
+    """
+    Compute the matrix needed to rotate vectors between two
+    standard inertial reference frames.
+
+    https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/irfrot.html
+
+    :param refa: index of first reference frame.
+    :param refb: index of second reference frame.
+    :return: rotation from frame A to frame B.
+    """
+    refa = ctypes.c_int(refa)
+    refb = ctypes.c_int(refb)
+    rotab = stypes.empty_double_matrix()
+    libspice.irfrot_(ctypes.byref(refa), ctypes.byref(refb), rotab)
+    # make sure to transpose to get back into c order from fortran ordering
+    return stypes.c_matrix_to_numpy(rotab).T
+
+
+@spice_error_check
+def irftrn(refa: str, refb: str) -> ndarray:
+    """
+    Return the matrix that transforms vectors from one specified
+    inertial reference frame to another.
+
+    https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/irftrn.html
+
+    :param refa: Name of reference frame to transform vectors FROM.
+    :param refb: Name of reference frame to transform vectors TO.
+    :return: REFA-to-REFB transformation matrix.
+    """
+    len_a = ctypes.c_int(len(refa))
+    len_b = ctypes.c_int(len(refb))
+    refa = stypes.string_to_char_p(refa)
+    refb = stypes.string_to_char_p(refb)
+    rotab = stypes.empty_double_matrix()
+    libspice.irftrn_(refa, refb, rotab, len_a, len_b)
+    # make sure to transpose to get back into c order from fortran ordering
+    return stypes.c_matrix_to_numpy(rotab).T
+
+
 @spice_error_check
 def isordv(array: Iterable[int], n: int) -> bool:
     """

spiceypy/tests/test_wrapper.py

@@ -5144,6 +5144,36 @@ def test_invort():
     npt.assert_array_almost_equal(m, mit)
 
 
+def test_irfnam():
+    assert spice.irfnam(1) == "J2000"
+    assert spice.irfnam(13) == "GALACTIC"
+    assert spice.irfnam(21) == "DE-143"
+
+
+def test_irfnum():
+    assert spice.irfnum("J2000") == 1
+    assert spice.irfnum("GALACTIC") == 13
+    assert spice.irfnum("DE-143") == 21
+
+
+def test_irfrot():
+    # get the rotation matrix from pxform
+    expected_rotate = spice.pxform("B1950", "J2000", 0.0)
+    # get hopefully the same rotation matrix from irfrot
+    fromfrm = spice.irfnum("B1950")
+    tofrm = spice.irfnum("J2000")
+    actual_rotate = spice.irfrot(fromfrm, tofrm)
+    npt.assert_array_almost_equal(actual_rotate, expected_rotate, decimal=4)
+
+
+def test_irftrn():
+    # get the rotation matrix from pxform
+    expected_rotate = spice.pxform("B1950", "J2000", 0.0)
+    # get hopefully the same rotation matrix from irfrot
+    actual_rotate = spice.irftrn("B1950", "J2000")
+    npt.assert_array_almost_equal(actual_rotate, expected_rotate, decimal=4)
+
+
 def test_isordv():
     assert spice.isordv([0, 1], 2)
     assert spice.isordv([0, 1, 2], 3)

spiceypy/utils/libspicehelper.py

@@ -1104,6 +1104,10 @@
 libspice.intmin_c.restype = c_int
 libspice.invert_c.argtypes = [(c_double * 3) * 3, (c_double * 3) * 3]
 libspice.invort_c.argtypes = [(c_double * 3) * 3, (c_double * 3) * 3]
+libspice.irfnam_.argtypes = [c_int_p, c_char_p, c_int]
+libspice.irfnum_.argtypes = [c_char_p, c_int_p, c_int]
+libspice.irfrot_.argtypes = [c_int_p, c_int_p, (c_double * 3) * 3]
+libspice.irftrn_.argtypes = [c_char_p, c_char_p, (c_double * 3) * 3, c_int, c_int]
 libspice.isordv_c.argtypes = [c_int_p, c_int]
 libspice.isordv_c.restype = c_int
 libspice.isrchc_c.argtypes = [c_char_p, c_int, c_int, c_void_p]