/[escript]/trunk/escript/py_src/unitsSI.py
ViewVC logotype

Contents of /trunk/escript/py_src/unitsSI.py

Parent Directory Parent Directory | Revision Log Revision Log


Revision 2448 - (show annotations)
Fri May 29 04:47:48 2009 UTC (9 years, 10 months ago) by ahallam
File MIME type: text/x-python
File size: 11044 byte(s)
Week 9: implemented cosine taper for wave function, need to work on direct method without lumping, wave propagation velocity is still not correct
1
2 ########################################################
3 #
4 # Copyright (c) 2003-2008 by University of Queensland
5 # Earth Systems Science Computational Center (ESSCC)
6 # http://www.uq.edu.au/esscc
7 #
8 # Primary Business: Queensland, Australia
9 # Licensed under the Open Software License version 3.0
10 # http://www.opensource.org/licenses/osl-3.0.php
11 #
12 ########################################################
13
14 __copyright__="""Copyright (c) 2003-2008 by University of Queensland
15 Earth Systems Science Computational Center (ESSCC)
16 http://www.uq.edu.au/esscc
17 Primary Business: Queensland, Australia"""
18 __license__="""Licensed under the Open Software License version 3.0
19 http://www.opensource.org/licenses/osl-3.0.php"""
20 __url__="https://launchpad.net/escript-finley"
21 __author__="Lutz Gross, l.gross@uq.edu.au"
22
23 ## @file unitsSI.py
24
25 """
26 some tools supporting physical units and conversion
27
28 @var __author__: name of author
29 @var __copyright__: copyrights
30 @var __license__: licence agreement
31 @var __url__: url entry point on documentation
32 @var __version__: version
33 @var __date__: date of the version
34
35 @var Yotta : prefix yotta, symbol: Y
36 @var Zetta : prefix zetta, symbol: Z
37 @var Exa : prefix exa, symbol: E
38 @var Peta : prefix peta, symbol: P
39 @var Tera : prefix tera, symbol: T
40 @var Giga : prefix giga, symbol: G
41 @var Mega : prefix mega, symbol: M
42 @var Kilo : prefix kilo, symbol: k
43 @var Hecto : prefix hecto, symbol: h
44 @var Deca : prefix deca, symbol: da
45 @var Deci : prefix deci, symbol: d
46 @var Centi : prefix centi, symbol: c
47 @var Milli : prefix milli, symbol: m
48 @var Micro : prefix micro, symbol: mu
49 @var Nano : prefix nano, symbol: n
50 @var Pico : prefix pico, symbol: p
51 @var Femto : prefix femto, symbol: f
52 @var Atto : prefix atto, symbol: a
53 @var Zepto : prefix zepto, symbol: z
54 @var Yocto : prefix yocto, symbol: y
55
56 @var km : unit of kilo meter
57 @var m : unit of meter
58 @var cm : unit of centi meter
59 @var mm : unit of milli meter
60 @var sec: unit of second
61 @var minute : unit of minute
62 @var h : unit of hour
63 @var day : unit of day
64 @var yr : unit of year
65 @var Myr : unit of mega year
66 @var Gyr : unit of giga year
67 @var gram : unit of gram
68 @var kg : unit of kilo gram
69 @var lb : unit of pound
70 @var ton : metric ton
71 @var A : unit of Ampere
72 @var Hz: unit of Hertz (frequenacy)
73 @var N: unit of Newton (force)
74 @var Pa: unit of Pascal (pressure, stress)
75 @var atm: unit of atmosphere (pressure)
76 @var J: unit of Joule (energy, work)
77 @var W: unit of Watt (power)
78 @var C: unit of Coulomb (electric charge)
79 @var V: unit of Volt (electric potential)
80 @var F: unit of Farad (capacitance)
81 @var Ohm: unit of Ohm (electric resistance)
82 @var K : unit of Kelvin (temperature)
83 @var Celsius: unit of Celsius (temperature)
84 @var Fahrenheit : unit of Fahrenheit (temperature)
85 @var R_Earth_equator: Earth's equatorial radius
86 @var R_Earth_poles: Earth's polar radius
87 @var R_Earth: Earth's radius
88 @var v_light: speed of light
89 @var pi: value of pi accurate to 10 decimal places
90 """
91 class Unit(object):
92 """
93 a general class to define a physical unit and convert from this unit to an appropriate SI unit.
94
95 L{Unit} object have a dual purpose: Firstly physical units can be combined through *,/ and ** to form new physical units or to add prefixes such as
96 Milli to m to form mm=Milli*m. Moreover, a given floating point number x (or any other arithmetic object) can be converted from the physical unit to
97 the SI system, eg. 10*mm to create the value for 10mm which is the float number 0.01 in the SI system. In addition, a value in the SI unit can be
98 converted back to the given unit, eg. to express 0.01m in physical units of mm use 0.01/mm which will return 10.
99 """
100 def __init__(self, name, longname,a ,b ):
101 """
102 initializes the physical unit
103
104 @param name: short name of the physical unit or prefix
105 @type name: C{str}
106 @param longname: long name of the physical unit or prefix
107 @type longname: C{str}
108 @param a: absolute value in transformation
109 @type a: C{float}
110 @param b: slop in translation
111 @type b: C{float}
112 """
113 self.setName(name)
114 self.setLongName(longname)
115 self.__a=a
116 self.__b=b
117
118 def __str__(self):
119 return self.getName()
120
121 def getName(self):
122 """
123 Returns the name of the physical unit
124
125 @return: name of the physical unit
126 @rtype: C{str}
127 """
128 return self.__name
129
130 def setName(self, name):
131 """
132 Sets the name of the physical unit
133
134 @param name: new name of the physical unit
135 @type name: C{str}
136 """
137 self.__name=name
138
139 def getLongName(self):
140 """
141 Returns the long name of the physical unit
142
143 @return: name of the physical unit
144 @rtype: C{str}
145 """
146 return self.__longname
147
148 def setLongName(self, name):
149 """
150 Sets the long name of the physical unit
151
152 @param name: new long name of the physical unit
153 @type name: C{str}
154 """
155 self.__longname=name
156
157 def __call__(self,x):
158 """
159 Converts a value x in the physical unit self to SI
160
161 @param x: value to convert
162 @type x: an arithmetic object
163 """
164 return self.__b*x+self.__a
165
166 def __mul__(self,other):
167 """
168 Performs self*other operation for two L{Unit} objects
169
170 @param other: an other physical unit
171 @type other: L{Unit}
172 @rtype: L{Unit} or C{NotImplemented}
173 """
174 if isinstance(other, Unit):
175 a=self(other(0.))
176 b=(self(other(1.))-a)
177 if isinstance(other, _PowUnit) or isinstance(self,_DivUnit) or isinstance(self, _PowUnit):
178 return _ProdUnit(self.getName()+" "+other.getName(),self.getLongName()+"*"+other.getLongName(),a ,b)
179 else:
180 return _ProdUnit(self.getName()+other.getName(),self.getLongName()+"*"+other.getLongName(),a ,b)
181 else:
182 return NotImplemented
183
184 def __rmul__(self,other):
185 """
186 Performs other*self operation
187
188 @param other: an other L{Unit} or an arithmetic object. if other is a arithmetic object such as C{float} other is assumed to be given in the
189 physical unit C{self} and is converted into the corresponding SI unit.
190 @type other: L{Unit} or
191 @rtype: L{Unit} of or an arithmetic object
192 """
193 if isinstance(other, Unit):
194 a=other(self(0.))
195 b=(other(self(1.))-a)
196 if isinstance(other, _PowUnit) or isinstance(self, _PowUnit) or isinstance(other, _DivUnit):
197 return _ProdUnit(other.getName()+" "+self.getName(),other.getLongName()+"*"+self.getLongName(),a ,b)
198 else:
199 return _ProdUnit(other.getName()+self.getName(),other.getLongName()+"*"+self.getLongName(),a ,b)
200 else:
201 return self(other)
202
203 def __div__(self,other):
204 """
205 Performs self*other operation for two L{Unit} objects
206
207 @param other: an other physical unit
208 @type other: L{Unit}
209 @rtype: L{Unit} or C{NotImplemented}
210 """
211 if isinstance(other, Unit):
212 if abs(self(0.))+abs(other(0.))>0:
213 raise ValueError,"Division of physical units requires 0 absolute values"
214 if isinstance(other, (_ProdUnit, _DivUnit)):
215 # X/(c*d) or X/(c/d) requires brackets:
216 return _DivUnit(self.getName()+"/("+other.getName()+")",self.getLongName()+"/("+other.getLongName()+")",0 , self(1.)/other(1.))
217 else:
218 return _DivUnit(self.getName()+"/"+other.getName(),self.getLongName()+"/"+other.getLongName(),0 , self(1.)/other(1.))
219 else:
220 return NotImplemented
221 def __rdiv__(self,other):
222 """
223 Performs other/self operation
224
225 @param other: an other L{Unit} or an arithmetic object
226 @type other: L{Unit} or an arithmetic object
227 @rtype: L{Unit} or an arithmetic object
228 """
229 if isinstance(other, Unit):
230 if abs(self(0.))+abs(other(0.))>0:
231 raise ValueError,"Division of physical units requires 0 absolute values"
232 if isinstance(self, (_ProdUnit, _DivUnit)):
233 # X/(a*b) or X/(a/b) requires brackets:
234 return _DivUnit(other.getName()+"/("+self.getName()+")",other.getLongName()+"/("+self.getLongName()+")",0 , other(1.)/self(1.))
235 else:
236 return _DivUnit(other.getName()+"/"+self.getName(),other.getLongName()+"/"+self.getLongName(),0 , other(1.)/self(1.))
237 else:
238 return (other-self(0.))/(self(1.)-self(0.))
239 def __pow__(self,other):
240 """
241 Performs self**other operation
242
243 @param other: an exponent
244 @type other: C{int} or C{float}
245 @rtype: L{Unit}
246 """
247 if isinstance(other, float) or isinstance(other, int):
248 if abs(self(0.))>0:
249 raise ValueError,"Power of physical unit requires 0 absolute values"
250 if isinstance(self, (_ProdUnit, _DivUnit, _PowUnit)):
251 return _PowUnit("("+self.getName()+")^%s"%other, "("+self.getLongName()+")^%s"%other, 0., self(1.)**other)
252 else:
253 return _PowUnit(self.getName()+"^%s"%other, self.getLongName()+"^%s"%other, 0., self(1.)**other)
254 else:
255 return NotImplemented
256
257 class _ProdUnit(Unit):
258 pass
259 class _DivUnit(Unit):
260 pass
261 class _PowUnit(Unit):
262 pass
263
264 #
265 # prefixes:
266 #
267 Yotta=Unit("Y","Yotta",0.,1.e24)
268 Zetta=Unit("Z","Zetta",0.,1.e21)
269 Exa=Unit("E","Exa",0.,1.e18)
270 Peta=Unit("P","Peta",0.,1.e15)
271 Tera=Unit("T","Tera",0.,1.e12)
272 Giga=Unit("G","Giga",0.,1.e9)
273 Mega=Unit("M","Mega",0.,1.e6)
274 Kilo=Unit("k","Kilo",0.,1.e3)
275 Hecto=Unit("h","Hecto",0.,1.e2)
276 Deca=Unit("da","Deca",0.,1.e1)
277 one=Unit("1","1",0.,1.)
278 Deci=Unit("d","Deci",0.,1.e-1)
279 Centi=Unit("c","Centi",0.,1.e-2)
280 Milli=Unit("m","Milli",0.,1.e-3)
281 Micro=Unit("mu","Micro",0.,1.e-6)
282 Nano=Unit("n","Nano",0.,1.e-9)
283 Pico=Unit("p","Pico",0.,1.e-12)
284 Femto=Unit("f","Femto",0.,1.e-15)
285 Atto=Unit("a","Atto",0.,1.e-18)
286 Zepto=Unit("z","Zepto",0.,1.e-21)
287 Yocto=Unit("y","Yocto",0.,1.e-24)
288 #
289 # length
290 #
291 m=Unit("m","meter",0.,1.)
292 km=Kilo*m
293 cm=Centi*m
294 mm=Milli*m
295 #
296 # time
297 #
298 sec=Unit("sec","second",0.,1.)
299 minute=Unit("min","minute",0.,60.)
300 h=Unit("h","hour",0.,60.*60.)
301 day=Unit("d","day",0.,60.*60.*24.)
302 yr=Unit("yr","year",0.,60.*60.*24.*365.2425)
303 Myr=Mega*yr
304 Gyr=Giga*yr
305 #
306 # mass
307 #
308 kg=Unit("kg","kg",0.,1.)
309 gram=Milli*kg
310 lb=Unit("lb","pound",0.,0.45359237)
311 ton=Kilo*kg
312 #
313 # electric current
314 #
315 A=Unit("A","Ampere",0.,1.)
316 #
317 # Temperature
318 #
319 K=Unit("K","Kelvin",0.,1.)
320 Celsius=Unit("C","Celsius",273.15,1.)
321 Fahrenheit=Unit("F","Fahrenheit",459.67*5./9.,5./9.)
322 #
323 # others
324 #
325 Hz=one/sec
326 N = Unit("N","Newton",0.,1.)
327 Pa = Unit("Pa","Pascal",0.,1.)
328 atm= Unit("atm","atmosphere",0.,101325.024)
329 J = Unit("J","Joule",0.,1.)
330 W= Unit("W","Watt",0.,1.)
331 C=Unit("C","Coulomb",0.,1.)
332 V = Unit("V","Volt",0.,1.)
333 F = Unit("F","Farad",0.,1.)
334 Ohm=Unit("Ohm","Ohm",0.,1.)
335 #
336 # some constants
337 #
338 R_Earth_equator=6378.1370*km
339 R_Earth_poles=6356.7523*km
340 R_Earth=(R_Earth_equator+R_Earth_poles)/2
341 v_light=299792458.*m/sec

  ViewVC Help
Powered by ViewVC 1.1.26