# 
msgid ""
msgstr ""
"Project-Id-Version: Modelica by Example 0.2.1\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2014-04-14 10:14-0400\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language-Team: LANGUAGE <LL@li.org>\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"

#: ../../source/behavior/equations/variables.rst:5
msgid "Variables"
msgstr ""

#: ../../source/behavior/equations/variables.rst:7
msgid ""
"As we saw in the previous section, a model definition typically contains "
"variable declarations.  The basic syntax for a variable declaration is "
"simply the \"type\" of the variable (which will be discussed shortly in the "
"section on :ref:`builtin-types`) followed by the name of the variable, "
"*e.g.*,"
msgstr ""

#: ../../source/behavior/equations/variables.rst:17
msgid ""
"Variables sharing the same type can be grouped together using the following "
"syntax:"
msgstr ""

#: ../../source/behavior/equations/variables.rst:24
msgid "A declaration can also be followed by a description, e.g.:"
msgstr ""

#: ../../source/behavior/equations/variables.rst:33
msgid "Variability"
msgstr ""

#: ../../source/behavior/equations/variables.rst:40
msgid "Parameters"
msgstr ""

#: ../../source/behavior/equations/variables.rst:42
msgid ""
"By default, variables declared inside a model are assumed to be continuous "
"variables (variables whose solution is generally smooth, but which may also "
"include discontinuities).  However, as we first saw in the section titled "
":ref:`getting-physical`, it is also possible to add the ``parameter`` "
"qualifier in front of a variable declaration and to indicate that the "
"variable is known *a priori*.  You can think of a parameter as \"input "
"data\" to the model that is constant with respect to time."
msgstr ""

#: ../../source/behavior/equations/variables.rst:54
msgid "Constants"
msgstr ""

#: ../../source/behavior/equations/variables.rst:56
msgid ""
"Closely related to the ``parameter`` qualifier is the ``constant`` "
"qualifier.  When placed in front of a variable declaration, the ``constant``"
" qualifier also implies that the value of the variable is known *a priori* "
"and is constant with respect to time.  The distinction between the two lies "
"in the fact that a ``parameter`` value can be changed from one simulation to"
" the next whereas the value of a ``constant`` cannot be changed once the "
"model is compiled.  The use of ``constant`` by a model developer ensures "
"that end users are not given the option to make changes to the ``constant``."
"  A ``constant`` is frequently used to represent physical quantities like "
":math:`\\pi` or the Earth's gravitational acceleration, which can be assumed"
" constant for most engineering simulations."
msgstr ""

#: ../../source/behavior/equations/variables.rst:70
msgid "Discrete Variables"
msgstr ""

#: ../../source/behavior/equations/variables.rst:74
msgid ""
"Another qualifier that can be placed in front of a variable declaration is "
"the ``discrete`` qualifier.  We have not yet shown any example where the "
"``discrete`` qualifier would be relevant.  However, it is included now for "
"completeness since it is the last remaining variability qualifier."
msgstr ""

#: ../../source/behavior/equations/variables.rst:83
msgid "Built-In Types"
msgstr ""

#: ../../source/behavior/equations/variables.rst:87
msgid ""
"Many of the examples so far referenced the ``Real`` type when declaring "
"variables.  As the name suggests, ``Real`` is used to represent real valued "
"variables (which will generally be translated into floating point "
"representations by a Modelica compiler).  However, ``Real`` is just one of "
"the four built-in types in Modelica."
msgstr ""

#: ../../source/behavior/equations/variables.rst:97
msgid ""
"Another of the built-in types is the ``Integer`` type.  This type is used to"
" represent integer values.  ``Integer`` variables have many uses including "
"representing the size of arrays (this use case will be discussed shortly in "
"an upcoming section on :ref:`vectors-and-arrays`)."
msgstr ""

#: ../../source/behavior/equations/variables.rst:103
msgid ""
"The remaining built-in types are ``Boolean`` (used to represent values that "
"can be either ``true`` or ``false``) and ``String`` (used for representing "
"character strings)."
msgstr ""

#: ../../source/behavior/equations/variables.rst:107
msgid ""
"Each of the built-in types restricts the possible values that a variable can"
" have.  Obviously, an ``Integer`` variable cannot have the value ``2.5``, a "
"``Boolean`` or ``String`` cannot be ``7`` and a ``Real`` variable cannot "
"have the value ``\"Hello\"``."
msgstr ""

#: ../../source/behavior/equations/variables.rst:115
msgid "Derived Types"
msgstr ""

#: ../../source/behavior/equations/variables.rst:119
msgid ""
"As we saw in the previous examples that introduced :ref:`physical-types`, it"
" is possible to \"specialize\" the built-in types.  This feature is used "
"mainly to modify the values associated with :ref:`attributes` like ``unit``."
"  The general syntax for creating derived types is:"
msgstr ""

#: ../../source/behavior/equations/variables.rst:131
msgid ""
"Frequently, the ``BaseTypeName`` will be one of the built-in types (*e.g.*, "
"``Real``).  But it can also be another derived type.  This means that "
"multiple levels of specialization can be supported, *e.g.*,"
msgstr ""

#: ../../source/behavior/equations/variables.rst:143
msgid "Enumerations"
msgstr ""

#: ../../source/behavior/equations/variables.rst:147
msgid ""
"An ``enumeration`` type is very similar to the ``Integer`` type.  An "
"``enumeration`` is typically used to define a type that can take on only a "
"limited set of specific values.  In fact, enumerations are not strictly "
"necessary in the language.  Their values can always be represented by "
"integers.  However, the ``enumeration`` type is safer and more readable than"
" an ``Integer``."
msgstr ""

#: ../../source/behavior/equations/variables.rst:154
msgid ""
"There are two built-in enumeration types.  The first of these is "
"``AssertionLevel`` and it is defined as follows:"
msgstr ""

#: ../../source/behavior/equations/variables.rst:164
msgid ""
"The significance of these values will be discussed in a forthcoming section "
"on :ref:`assertions`."
msgstr ""

#: ../../source/behavior/equations/variables.rst:167
msgid ""
"The other built-in enumeration is ``StateSelect`` and it is defined as "
"follows:"
msgstr ""

#: ../../source/behavior/equations/variables.rst:177
msgid "Attributes"
msgstr ""

#: ../../source/behavior/equations/variables.rst:181
msgid ""
"So far in this chapter we have mentioned attributes (*e.g.*, ``unit``), but "
"we haven't discussed them in detail. For example, *which* attributes are "
"present on a given variable?  This depends on the type of the variable (and "
"which built-in and derived types it is based on).  The following table "
"introduces all the possible attributes indicating their types (*i.e.*, what "
"type of value can be given for that attribute), which types they can be "
"associated with and finally a brief description of the attribute:"
msgstr ""

#: ../../source/behavior/equations/variables.rst:203
msgid "Attributes of ``Real``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:210
#: ../../source/behavior/equations/variables.rst:340
#: ../../source/behavior/equations/variables.rst:393
#: ../../source/behavior/equations/variables.rst:425
msgid "``quantity``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:206
#: ../../source/behavior/equations/variables.rst:336
#: ../../source/behavior/equations/variables.rst:389
#: ../../source/behavior/equations/variables.rst:421
msgid "A textual description of what the variable represents"
msgstr ""

#: ../../source/behavior/equations/variables.rst:208
#: ../../source/behavior/equations/variables.rst:306
#: ../../source/behavior/equations/variables.rst:338
#: ../../source/behavior/equations/variables.rst:391
#: ../../source/behavior/equations/variables.rst:423
#: ../../source/behavior/equations/variables.rst:435
msgid "**Default**: ``\"\"``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:210
#: ../../source/behavior/equations/variables.rst:290
#: ../../source/behavior/equations/variables.rst:308
#: ../../source/behavior/equations/variables.rst:340
#: ../../source/behavior/equations/variables.rst:393
#: ../../source/behavior/equations/variables.rst:425
#: ../../source/behavior/equations/variables.rst:437
msgid "**Type**: ``String``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:227
#: ../../source/behavior/equations/variables.rst:354
#: ../../source/behavior/equations/variables.rst:407
#: ../../source/behavior/equations/variables.rst:437
msgid "``start``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:213
msgid ""
"The ``start`` attribute has many uses.  The main purpose of the ``start`` "
"attribute (as discussed extensively in the section on :ref:`initialization`)"
" is to provide \"fallback\" initial conditions for state variables (see "
"``fixed`` attribute for more details)."
msgstr ""

#: ../../source/behavior/equations/variables.rst:218
msgid ""
"The ``start`` attribute may also be used as an initial guess if the variable"
" has been chosen as an iteration variable."
msgstr ""

#: ../../source/behavior/equations/variables.rst:221
msgid ""
"Finally, if a ``parameter`` doesn't have an explicit value specified, the "
"value of the ``start`` attribute will be used as the default value for the "
"``parameter``."
msgstr ""

#: ../../source/behavior/equations/variables.rst:225
#: ../../source/behavior/equations/variables.rst:316
#: ../../source/behavior/equations/variables.rst:352
#: ../../source/behavior/equations/variables.rst:405
msgid "**Default**: ``0.0``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:227
#: ../../source/behavior/equations/variables.rst:252
#: ../../source/behavior/equations/variables.rst:262
#: ../../source/behavior/equations/variables.rst:272
#: ../../source/behavior/equations/variables.rst:318
msgid "**Type**: ``Real``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:252
#: ../../source/behavior/equations/variables.rst:362
#: ../../source/behavior/equations/variables.rst:415
msgid "``fixed``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:230
msgid ""
"The ``fixed`` attribute changes the way the ``start`` attribute is used when"
" the ``start`` attribute is used as an initial condition.  Normally, the "
"``start`` attribute is considered a \"fallback\" initial condition and only "
"used if there are insufficient initial conditions explicitly specified in "
"the ``initial equation`` sections.  However, if the ``fixed`` attribute is "
"set to ``true``, then the ``start`` attribute is treated as if it was used "
"as an explicit ``initial equation`` (*i.e.,* it is no longer used as a "
"fallback, but instead treated as a strict initial condition)."
msgstr ""

#: ../../source/behavior/equations/variables.rst:241
msgid ""
"Another, more obscure, use of the ``fixed`` attribute is for \"computed "
"parameters\".  In rare cases where a ``parameter`` cannot be initialized "
"explicitly, it is possible to provide a general equation for the parameter "
"in an ``initial equation`` section. But in cases where the ``parameter`` is "
"initialized in this way, the ``fixed`` attribute for the parameter variable "
"must be set to ``false``."
msgstr ""

#: ../../source/behavior/equations/variables.rst:249
#: ../../source/behavior/equations/variables.rst:359
#: ../../source/behavior/equations/variables.rst:412
msgid ""
"**Default**: ``false`` (except for ``parameter`` variables, where it is "
"``true`` by default)"
msgstr ""

#: ../../source/behavior/equations/variables.rst:262
#: ../../source/behavior/equations/variables.rst:372
msgid "``min``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:255
#: ../../source/behavior/equations/variables.rst:365
msgid ""
"The ``min`` attribute is used to specify the minimum allowed value for a "
"variable.  This attribute can be used by editors and compilers in various "
"ways to inform users or developers about potentially invalid input data or "
"solutions."
msgstr ""

#: ../../source/behavior/equations/variables.rst:260
#: ../../source/behavior/equations/variables.rst:370
msgid "**Default**: -:math:`\\infty`"
msgstr ""

#: ../../source/behavior/equations/variables.rst:272
#: ../../source/behavior/equations/variables.rst:383
msgid "``max``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:265
#: ../../source/behavior/equations/variables.rst:375
msgid ""
"The ``max`` attribute is used to specify the maximum allowed value for a "
"variable.  This attribute can be used by editors and compilers in various "
"ways to inform users or developers about potentially invalid input data or "
"solutions."
msgstr ""

#: ../../source/behavior/equations/variables.rst:270
#: ../../source/behavior/equations/variables.rst:380
msgid "**Default**: :math:`\\infty`"
msgstr ""

#: ../../source/behavior/equations/variables.rst:290
msgid "``unit``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:275
msgid ""
"As discussed extensively in this chapter, variables can have physical units "
"associated with them.  There are rules about how these units are expressed, "
"but the net result is that by using the ``unit`` attribute it is possible "
"check models to make sure that equations are physically consistent.  A value"
" of ``\"1\"`` indicates the value has no physical units.  On the other hand,"
" a value of ``\"\"`` (the default value if no value is given) indicates that"
" the physical units are simply unspecified.  The difference between "
"``\"1\"`` and ``\"\"`` is that the former is an explicit statement that the "
"quantity is dimensionless (has not units) while the latter indicates that "
"the quantity may have physical units but they are left unspecified."
msgstr ""

#: ../../source/behavior/equations/variables.rst:288
msgid "**Default**: ``\"\"`` (*i.e.,* no physical units specified)"
msgstr ""

#: ../../source/behavior/equations/variables.rst:308
msgid "``displayUnit``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:293
msgid ""
"While the ``unit`` attribute describes what physical units should be "
"associated with the value of a variable, the ``displayUnit`` expresses a "
"preference for what units should be used when displaying the value of a "
"variable.  For example, the SI unit for pressure is *Pascals*.  However, "
"standard atmospheric pressure is 101,325 *Pascals*.  When entering, "
"displaying or plotting pressures it may be more convenient to use *bars*."
msgstr ""

#: ../../source/behavior/equations/variables.rst:301
msgid ""
"The ``displayUnit`` attribute doesn't affect the value of a variable or the "
"equations used to simulate a model.  It only affects the *rendering* of "
"those values by potentially transforming them into more convenient units for"
" display."
msgstr ""

#: ../../source/behavior/equations/variables.rst:318
msgid "``nominal``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:311
msgid ""
"The ``nominal`` attribute is used to specify a nominal value for a variable."
"  This nominal value is generally used in numerical calculations to perform "
"various types of scaling used to avoid round-off or truncation error."
msgstr ""

#: ../../source/behavior/equations/variables.rst:330
msgid "``stateSelect``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:321
msgid ""
"The ``stateSelect`` attribute is used as a hint to Modelica compilers about "
"whether a given variable should be chosen as a state (in cases where there "
"is a choice to be made).  As discussed previously in the section on "
":ref:`enumerations`, the possible values for this attribute are ``never``, "
"``avoid``, ``default``, ``prefer`` and ``always``."
msgstr ""

#: ../../source/behavior/equations/variables.rst:328
msgid "**Default**: ``default``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:330
msgid "**Type**: ``StateSelect`` (enumeration, see :ref:`enumerations`)"
msgstr ""

#: ../../source/behavior/equations/variables.rst:333
msgid "Attributes of ``Integer``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:343
msgid ""
"It is worth noting that an ``Integer`` variable can be chosen as a state "
"variable or as an iteration variable.  Under these circumstances, the "
"``start`` attribute may be used by a compiler in the same was as it is for "
"``Real`` variables (*see previous discussion of* :ref:`fixed-attribute`)"
msgstr ""

#: ../../source/behavior/equations/variables.rst:349
#: ../../source/behavior/equations/variables.rst:402
msgid ""
"In the case of a ``parameter``, the ``start`` attribute will (as usual) be "
"used as the default value for the ``parameter``."
msgstr ""

#: ../../source/behavior/equations/variables.rst:354
#: ../../source/behavior/equations/variables.rst:372
#: ../../source/behavior/equations/variables.rst:382
msgid "**Type**: ``Integer``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:357
#: ../../source/behavior/equations/variables.rst:410
msgid "*see previous discussion of* :ref:`fixed-attribute`"
msgstr ""

#: ../../source/behavior/equations/variables.rst:362
#: ../../source/behavior/equations/variables.rst:407
#: ../../source/behavior/equations/variables.rst:415
msgid "**Type**: ``Boolean``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:386
msgid "Attributes of ``Boolean``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:396
msgid ""
"It is worth noting that an ``Boolean`` variable can be chosen as a state "
"variable or as an iteration variable.  Under these circumstances, the "
"``start`` attribute may be used by a compiler in the same was as it is for "
"``Real`` variables (*see previous discussion of* :ref:`fixed-attribute`)"
msgstr ""

#: ../../source/behavior/equations/variables.rst:418
msgid "Attributes of ``String``"
msgstr ""

#: ../../source/behavior/equations/variables.rst:428
msgid ""
"Technically, a ``String`` could be chosen as a state variable (or even an "
"iteration variable), but in practice this never happens. So for a ``String``"
" variable the only practical use of the ``start`` attribute is to define the"
" value of a ``parameter`` (that happens to have the type of ``String``) if "
"no explicit value for the parameter is given."
msgstr ""

#: ../../source/behavior/equations/variables.rst:439
msgid ""
"It is worth noting that :ref:`derived-types` retain the attributes of the "
"built-in type that they are ultimately derived from.  Also, although the "
"type of, for example, the ``min`` attribute on a ``Real`` variable is listed"
" having the type ``Real`` it should be pointed out explicitly that "
"attributes cannot themselves have attributes.  In other words, the ``start``"
" attribute doesn't have a ``start`` attribute."
msgstr ""

#: ../../source/behavior/equations/variables.rst:450
msgid "Modifications"
msgstr ""

#: ../../source/behavior/equations/variables.rst:454
msgid ""
"So far, we've seen two types of modifications.  The first is when we change "
"the value of an attribute, *e.g.,*"
msgstr ""

#: ../../source/behavior/equations/variables.rst:464
msgid ""
"In this case, we are creating a variable ``x`` of type ``Real``.  But rather"
" than leaving it \"as is\", we then apply a modification to ``x``.  "
"Specifically, we \"reach inside\" of ``x`` and change the ``start`` "
"attribute value.  In this example, we are only going one level into ``x`` to"
" make our modification.  But as we will see in our next example, it is "
"possible to make modifications at arbitrary depths."
msgstr ""

#: ../../source/behavior/equations/variables.rst:472
msgid ""
"The other case where we have seen modifications was in the section on :ref"
":`avoiding-repetition`.  There we saw modification used in conjunction with "
"``extends`` clauses, *e.g.,*"
msgstr ""

#: ../../source/behavior/equations/variables.rst:482
msgid ""
"Here, the modification is applied to elements that were inherited from the "
"``QuiescentModelWithInheritance`` model.  As with modifications to "
"attributes, the element being modified (a model in this case) is followed by"
" parentheses and inside those parentheses we specify the modifications we "
"wish to make."
msgstr ""

#: ../../source/behavior/equations/variables.rst:490
msgid ""
"It is worth noting that modifications can be nested arbitrarily deep. For "
"example, imagine we wanted to modify the ``start`` attribute for the "
"variable ``x`` inherited from the ``QuiescentModelWithInheritance`` model.  "
"In Modelica, such a modification would be made as follows:"
msgstr ""

#: ../../source/behavior/equations/variables.rst:500
msgid ""
"Here we first \"reach inside\" the ``QuiescentModelWithInheritance`` model "
"to modify the contents that we \"inherit\" from it (``x`` in this case) and "
"then we \"reach inside\" ``x`` to modify the value of the ``start`` "
"attribute."
msgstr ""

#: ../../source/behavior/equations/variables.rst:505
msgid ""
"One of the central themes of Modelica is support for reuse and avoiding the "
"need to \"copy and paste\" code.  Modifications are one of the essential "
"features in Modelica that support reuse.  We'll learn about others in future"
" sections."
msgstr ""

#: ../../source/behavior/equations/variables.rst:35
msgid "parameter"
msgstr ""

#: ../../source/behavior/equations/variables.rst:51
msgid "constant"
msgstr ""

#: ../../source/behavior/equations/variables.rst:72
msgid "discrete"
msgstr ""

#: ../../source/behavior/equations/variables.rst:85
msgid "Real"
msgstr ""

#: ../../source/behavior/equations/variables.rst:93
msgid "Integer"
msgstr ""

#: ../../source/behavior/equations/variables.rst:94
msgid "Boolean"
msgstr ""

#: ../../source/behavior/equations/variables.rst:95
msgid "String"
msgstr ""

#: ../../source/behavior/equations/variables.rst:117
msgid "derived types"
msgstr ""

#: ../../source/behavior/equations/variables.rst:125
msgid "type"
msgstr ""

#: ../../source/behavior/equations/variables.rst:145
msgid "enumeration"
msgstr ""

#: ../../source/behavior/equations/variables.rst:157
msgid "AssertionLevel"
msgstr ""

#: ../../source/behavior/equations/variables.rst:158
msgid "assertion levels"
msgstr ""

#: ../../source/behavior/equations/variables.rst:179
msgid "attributes"
msgstr ""

#: ../../source/behavior/equations/variables.rst:190
msgid "quantity attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:191
msgid "start attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:192
msgid "fixed attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:193
msgid "min attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:194
msgid "max attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:195
msgid "unit attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:196
msgid "displayUnit attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:197
msgid "nominal attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:198
msgid "stateSelect attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:452
msgid "modifications"
msgstr ""

#: ../../source/behavior/equations/variables.rst:457
#: ../../source/behavior/equations/variables.rst:476
#: ../../source/behavior/equations/variables.rst:488
msgid "modification"
msgstr ""

#: ../../source/behavior/equations/variables.rst:457
msgid "attribute"
msgstr ""

#: ../../source/behavior/equations/variables.rst:458
msgid "attribute modification"
msgstr ""

#: ../../source/behavior/equations/variables.rst:476
msgid "extends"
msgstr ""

#: ../../source/behavior/equations/variables.rst:488
msgid "hierarchical"
msgstr ""
