Unit conversion fix

scimath/units/acceleration.py

@@ -9,6 +9,9 @@
 # Thanks for using Enthought open source!
 
 """ Define units of acceleration
+
+Symbols defined: feet_per_second_squared, meters_per_second_squared [and aliases]
+
 """
 
 #####################################################################

scimath/units/angle.py

@@ -9,6 +9,10 @@
 # Thanks for using Enthought open source!
 
 """ Define units of angle (dimensionless with meaning)
+
+Symbols defined: circle, degree, grad, quadrant, mil, right_angle, radian, revolution, sextant, sign, turn
+                 minute, second, [and aliases]
+
 """
 
 #############################################################################

scimath/units/area.py

@@ -18,6 +18,13 @@
 
 from .length import meter, centimeter, inch, foot, mile
 
+""" Define units of area
+
+Symbols defined: acre, hectare, 
+                 barn, 
+                 square_centimeter, square_foot, square_inch, square_meter, square_mile [and aliases]
+
+"""
 
 #
 # Definitions of common area units

scimath/units/density.py

@@ -9,10 +9,14 @@
 # Thanks for using Enthought open source!
 
 """ Defines units of density
+
 Derived from: units/density.py [pyre system]
               Michael A.G. Aivazis
               California Institute of Technology
               (c) 1998-2003
+
+Symbols defined: grams_per_cubic_centimeter, kilograms_per_cubic_meter, lb_per_gal [and aliases]
+
 """
 
 #############################################################################

scimath/units/dimensionless.py

@@ -8,6 +8,12 @@
 #
 # Thanks for using Enthought open source!
 
+""" Defines units of dimensionless
+
+Symbols defined: fractional, parts_per_million, parts_per_one, percent [and aliases]
+
+"""
+
 from copy import copy
 from scimath.units.SI import dimensionless
 from scimath.units.unit import one, dim

scimath/units/electromagnetism.py

@@ -8,6 +8,19 @@
 #
 # Thanks for using Enthought open source!
 
+""" Defines units of electromagnetism
+
+Symbols defined: ampere, milli_ampere,
+                 farad, micro_farad, pico_farad,
+                 henry,
+                 ohm, ohm_meter, ohmm,
+                 siemen, mSiemen, siemens_per_meter,
+                 tesla,
+                 volt, milivolt,
+                 weber [and aliases]
+
+"""
+
 from copy import copy
 
 from scimath.units.SI import ampere, coulomb, farad, henry, joule, ohm, \

scimath/units/energy.py

@@ -30,6 +30,13 @@
 #     The NIST Reference on Constants, Units and Uncertainty,
 #         http://physics.nist.gov/cuu
 #
+# Symbols defined: Btu, 
+#                  Calorie, calorie, 
+#                  electron_volt, 
+#                  erg, 
+#                  foot_pound, 
+#                  horse_power_hour, kilowatt_hour [and aliases]
+#
 
 
 Btu = 1055 * joule

scimath/units/force.py

@@ -8,6 +8,12 @@
 #
 # Thanks for using Enthought open source!
 
+""" Defines units of force
+
+Symbols defined: lbf, lbs, N [and aliases]
+
+"""
+
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 #
 #                             Michael A.G. Aivazis

scimath/units/frequency.py

@@ -9,6 +9,8 @@
 # Thanks for using Enthought open source!
 
 """ Defines units of frequency
+
+Symbols defined: hertz, kilohertz, rpm [and aliases]
 """
 
 #############################################################################

scimath/units/length.py

@@ -13,6 +13,13 @@
               Michael A.G. Aivazis
               California Institute of Technology
               (c) 1998-2003
+
+Symbols defined: kilo-, centi-, milli-, micro-, nano-, pico-, meter,
+                 inch, foot, yard, mile,
+                 fathom, nautical_mile,
+                 angstrom, fermi, survey_foot, us_foot, us_feet,
+                 astronomical_unit, light_year, parsec [and aliases]
+
 """
 
 #############################################################################

scimath/units/mass.py

@@ -9,10 +9,16 @@
 # Thanks for using Enthought open source!
 
 """ Defines units of mass
+
 Derived from: units/mass.py [pyre system]
               Michael A.G. Aivazis
               California Institute of Technology
               (c) 1998-2003
+
+Symbols defined: centigram, gram, kilogram, milligram, 
+                 metric_ton, ton,  
+                 ounce, pound [and aliases]
+
 """
 
 #############################################################################

scimath/units/power.py

@@ -22,6 +22,7 @@
 # Definitions of common power units
 # Data taken from Appendix F of Halliday, Resnick, Walker, "Fundamentals of Physics",
 #     fourth edition, John Willey and Sons, 1993
+# Symbols defined: kilowatt, horsepower [and aliases]
 
 kilowatt = kilo * watt
 kw = kilowatt

scimath/units/pressure.py

@@ -29,9 +29,12 @@
 #
 #     The NIST Reference on Constants, Units and Uncertainty,
 #         http://physics.nist.gov/cuu
+# 
+# Symbols defined: pascal, kPa, MPa, GPa, inHg,
+#                  bar, kilobar, millibar, torr, atmosphere,
+#                  pounds_per_square_inch [and aliases]
 #
 
-
 # aliases
 
 Pa = pascal

scimath/units/quantity.py

@@ -303,8 +303,7 @@ def propagate_data_changes(self):
             return
 
         # Replace the predecessor's data with converted data.
-        new_quantity = self.change_unit_system(predecessor.units)
-        predecessor.data = new_quantity.data
+        predecessor.data = units_convert(self.data, self.units, predecessor.units)
 
         # Recursively continue propagating.
         predecessor.propagate_data_changes()

scimath/units/speed.py

@@ -9,10 +9,15 @@
 # Thanks for using Enthought open source!
 
 """ Defines units of density.
+
 Derived from: units/density.py [pyre system]
               Michael A.G. Aivazis
               California Institute of Technology
               (c) 1998-2003
+
+Symbols defined: feet_per_second, meters_per_second, kilometers_per_second, miles_per_hour,
+                 knot [and aliases]
+
 """
 
 #############################################################################

scimath/units/substance.py

@@ -16,6 +16,11 @@
 #
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+""" Defines units of substance
+
+Symbols defined: mole, kmole [and aliases]
+"""
+
 from .SI import mole, kilo
 
 

scimath/units/temperature.py

@@ -16,6 +16,12 @@
 #
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+""" Defines units of temperature
+
+Symbols defined: celsius, fahrenheit, kelvin, rankine [and aliases]
+
+"""
+
 from scimath.units.unit import unit
 
 # Tk = Tk

scimath/units/tests/test_units.py

@@ -197,6 +197,15 @@ def test_propagation(self):
         self.assertAlmostEqual(30., q1.data, 1,
                                "Propagation test expected data 30, got %s" % str(q1.data))
 
+    def test_propagation2(self):
+        """ Tests data propagation for a single converted quantity. """
+
+        q1 = Quantity(10.0, units='ft', family_name='depth')
+        q2 = q1.change_unit_system('METRIC')
+        q2.data = 2 * q2.data
+        q2.propagate_data_changes()
+        self.assertAlmostEqual(q1.data, 20.0)
+
     def test_get_original(self):
 
         q1 = Quantity(10, units='m', family_name='depth')

scimath/units/time.py

@@ -13,6 +13,10 @@
               Michael A.G. Aivazis
               California Institute of Technology
               (c) 1998-2003
+
+Symbols defined: milli-, micro-, nano-, pico-, second,
+                 minute, hour, day, week, year [and aliases]
+
 """
 
 #############################################################################

scimath/units/volume.py

@@ -15,6 +15,12 @@
               Michael A.G. Aivazis
               California Institute of Technology
               (c) 1998-2003
+
+Symbols defined: cubic_centimeter, cubic_foot, cubic_meter,
+                 liter, barrel,
+                 us_pint,
+                 us_fluid_ounce, us_fluid_quart, us_fluid_gallon [and aliases]
+
 """
 #############################################################################
 # Imports: