Dymola release notes

News in version 6.1

Modeling and simulation

• Initial condition can more easily be specified for variables. The fixed-attribute is shown similar to a checkbox, in front of the start-value. Clicking on the checkbox shows a popup-menu where you can select true/false/inherited.
  The fixed-attribute is described in Modelica and a value of true means that the start-value must be satisfied during initialization, whereas false means that the start-value is only intended as a guess-value for a non-linear solver. Inherited means that the fixed modifier is removed, and as a consequence, fixed modifier is set from other levels. The actual value with description is shown in the popup-menu.

  This dialog entry for start values is activated if one of following is true:

  • The default start-value is a non-final scalar literal.
  • The actual modifier sets the start-value.
  • The variable declaration is annotated with annotation(Dialog(initialDialog=true)).
  Note: Dymola 6.0b used a tri-state checkbox instead of a menu for this.

  Advanced users: The popup-menu can also show the state-selection attribute. This is controlled with annotation(Dialog(stateDialog=true, initialDialog=true)).

• User commands are now primarily found relative to the top of the package hierarchy and not relative to the model. (The other form is supported for compatibility reasons.) This implies that there is no need to move the scripts when encrypting a package. The menu entry "Add command" also uses this to construct relative paths to scripts.
• Dymola can call functions written in Java - both interactively and from models. (Java and any other Sun trademarks referred to or displayed in the document are trademarks or registered trademarks of Sun Microsystem, Inc. in the U.S. or other countries.)

  This requires that you:

  • Install either Java Development Kit or J2SE Software Development Kit. It is not sufficient to install the Java Runtime Environment.
  • The environment variable JAVA_HOME should point to this directory.
  • From Modelica externally declare the functions written in Java.
  • Have the Dymola license option for Java interface.
  The functions must be static member functions and the syntax in Modelica is:

  function f
    input Real u;
    output Real y;
    external "Java" y='MyPackage.MyClass.Myfunction'(u);
  end f;
  

  For interactive calls it is possible to call Dymola's interpreter from Java. Further documentation is found in the Dymola 6 Additions manual.
• Selection of iteration variables based on a confidence number for guess values.
  • The initialization problem often involves nonlinear algebraic loops. When solving a nonlinear system of equations, it is important that the iteration variables have good start values to guarantee convergence as well as convergence to the desired solution in case the nonlinear problem has several solutions. Dymola decreases the size of a nonlinear system by eliminating variables by tearing. It is thus a good idea to eliminate variables without start values or variables having less confident start values and keep as iteration variables those variables having more confident start values. Dymola now introduces a natural way to estimate the confidence of start values.
  • Models are typically built by composing components. The components may include settings for start values. If the top model sets parameters or start values of the components, the idea is to improve the model, not make it worse. When building the top model we usually have better and more specific information than when the component models were built. Thus it is reasonable to have more confidence in start values being set from higher hierarchical levels of the model. This approach gives both the model developers and the users good control possibilities. Changing a start value is expected to have an immediate effect.
  • A model has a hierarchical component structure. Each component of a model can be given a unique model component hierarchy level number. The top level model has a level number of 1. The level number increases by 1 for each level down in the model component hierarchy. The model component hierarchy level number is used to give start values a confidence number, where a lower number means that the start value is more confident.  Loosely, if the start value is set or modified on level i then the confidence number is i. If a start value is set by a possibly hierarchical modifier at the top level, then this start value has the highest confidence, namely 1 irrespectively on what level, the variable itself is declared.
  • The feature can be disabled by setting Advanced.UseConfidenceNumberForStartValues = false. It has been possibly to manually activate this since Dymola 6.0b. However, the feature is now improved and on by default.
• Dymola has a feature for checking of units. It is enabled by setting the flag Advanced.CheckUnits = true and it is active when checking a package, function or model as well as when translating a model for simulation. It includes checking of unit strings and unit compatibility of equations. Currently Dymola makes a relaxed checking. It means that an empty unit string, "", is interpreted as unknown unit. Also number literals are interpreted to have unknown unit. The unknown unit is propagated according to simple rules;

  unknown unit * "unit1" -> unknown unit
  unknown unit + "unit1" -> "unit1"
  

• The plot-browser preserves the open subtrees: when simulating, changing search filter, toggling compare results, etc.
• A model may specify that a function should be run before a component of the model is checked, translated or simulated. This could be used to verify structural parameters, or external data before using them. The function to be called is specified in an annotation in the following form:

  model M
    parameter String s="";
    annotation(preInstantiate=MyPackage.foo(s));
  end M;
  

  Notes:
  • This is only intended as a help and there is no absolute guarantee that this function will be called. It is not intended for e.g. license-checking.
  • Any parameters used must be possible to evaluate to literals.
  • Any parameters used must be top-level parameters in the model, e.g. you cannot use component.s.
  • Conditional components first have their condition evaluated. If the condition is false the component is not present and the preInstantiate function is not called.

Graphical editor

• Possible to directly change the description text when duplicating or renaming a class. It is always possible to change the description using Edit/Attributes.
• Bus modeling: It is possible to draw connections from a connector back to itself. This allows signals on a bus to be re-routed.
• The expandable connector dialog has been modified such that <New variable> is no longer present in the tree. To add a new name you should instead click on <Add variable> (which also opens the list of existing variables used in other models).
• Hiding of disabled conditional connectors and components enabled by default. Disabled conditional model components are rendered with a dotted rectangle. This avoids dangling connections to the disabled components. Top-level connectors are always drawn in the diagram layer, even if disabled.
• In Edit/Attributes/Graphics, component scale=0.1 is used as default if you change the coordinate system. For models with a non-square coordinate system, this change will give a natural component shape.

Libraries

• ModelManagement package is introduced. The package contains

  Check

  Utility for unit checking, style checking and regression testing, including condition coverage and class coverage analysis.


Regression testing - Regression testing is a utility to assist with regression testing of libraries. It is performed to detect unintended changes in the behaviour of models due to updates and rewriting of code. The regression testing feature of ModelManagement allows a user to easily set up a test suite for regression testing of a library in a straight forward way. It also produces a html report summarizing the result of the test.
Class coverage - The class coverage analysis determines how well the test suite covers the classes in the library under test. The result is reported in the regression test log.
Condition coverage - To ensure that all conditional statements in models are tested, conditions that don't have both true and false value in any test case are logged.
Variable unit checking - Dymola has a feature for checking of variable units.
Style checking - Style checking is a feature for checking a library according to style guidelines. It outputs a html log file that reports style errors in the checked library. It can be customized by the user to only check for specific issues related to library development, e.g. missing description strings, missing html documentation etc.
Compare
Feature for model comparison
Structure
Routines for accessing the model structure and content (abstract syntax tree - AST) and the instantiated AST
NOTE: ModelManagement is a licensed library that requires the Model management option.
• The Model calibration feature has been extended with the function Design.Calibration.staticCalibrate to support easy setup of calibration to tune static characteristics. It is described in more detail in the document Dymola 6 Additions and requires the ModelCalibration option.
• Some old libraries which use Modelica 1.6 have been removed from the distribution, for example the light (free) versions of the Hydraulics and Pneumatics libraries; the versions for Modelica 2.x (the default) are still part of the distribution.
• Some minor corrections in the Modelica standard library 2.2.1, as described in the top-level revision notes. This version corresponds to the Modelica Association maintenance branch at the time of release.

Environment

• Support for compiling models with Visual Studio 2005:
  • Professional editions: fully supported in standard configuration.
  • Express edition: compilation works if DDE-coupling is not selected. DDE-coupling requires an additional installation of the Windows SDK. Step 4 and 5 are optional and "Program files" is localization dependent.
• Improved reading of Modelica packages. In some Windows network environments, reading could previously be very slow due to checking of Access Control Lists. The checking of access rights has now been optimized. In some cases files were incorrectly marked as read-only; this has been corrected.
• Improved handling of result files. Especially when reading many result files the total memory use of Dymola has been reduced.
• Dymola defines environment variable DYMOLAWORK which value is the Dymola work directory. This is the default location where Dymola starts.
• Dymola on Windows can support "borrowing", the possibility to transfer a license from a license server to laptop for a limited period of time. Please contact sales@dynasim.se for further information.
• Dymola is supported on 64-bit Windows XP. However, Dymola is a 32-bit application also in this environment.
• Dymola is supported on Windows Vista.
• Dymola supports Matlab version 7.3 (R2006b).
• A prototype of an interface to LabView from National Instruments is available. Please contact Dynasim if you want additional information.
• A prototype of an interface to OPC Data Access is available (see http://www.opcfoundation.org/). Please contact Dynasim if you want additional information.

Documentation

• The Dymola 6 Additions Manual has been updated with the following sections:

  Recent features in Dymola

  • Java interface

  Model Management

  • Model and library checking
  • Model comparison
  • Model structure

  Model calibration

  • Static calibration

News in version 6.0d

• Improved connect dialog. The dialog is used for connecting to expandable connectors (and hierarchical connectors in general), and for incorrect connections.

  In the example below we have connected from the output y of the component mSource1 to the expandable connector bus. We are then given a choice of what variable on the bus to connect to and can select '<Add variable>' to browse for existing connections to 'bus' in other models, or click on '<New variable>' to construct a new variable.

• Easy to build model templates using replaceable components:
  • Drag and drop of partial models construct replaceable components.
  • For a replaceable component it is possible to modify the default class with the context-menu 'Change Class'.
  • The context-menu Edit/Attributes for component make it possible to set and modify constraining class (and replaceable attribute), both for the original declaration and a redeclare.
  As an example consider building an electrical test-template for Resistor, Capacitor, Inductor. This can be done by dragging in a OnePort and you then get a message
  By building the circuit in the usual way one then gets
  and can then change the default to Resistor using "Change class/All matching choices" in the context-menu of load.

  Alternatively one can modify replaceable and constraining class in the Attributes-context menu.

  Use the tool to browse for the constraining class. This icon is used in general to activate a class-browser.

  Both alternatives can give the same model as result. The difference is whether you find it more convenient to build the template directly, or want to start by building a actual model, test it, and then turn it into a template with replaceable components.

• Easier to use model templates:
  • The list in the context-menu 'Change Class' has a separator between top-level packages, and a status-message indicating the full path of each class. The full path was previously only available as a what's this text (available by pressing Shift-F1 on the entry).
  • The list in the context-menu 'Change Class' is hiearchical (in one level) to combine models that are parameter sets (i.e. comprised solely of an extends-clause with modifiers for parameter changes).
• Improvement for the Commands menu:
  • The Commands menu has been extended with the choice 'Organize Commands' that allows you to reorder, remove, and modify the existing commands.
  • Commands in the Commands menu can be inheritable to models extending from it. The command must either specify that it is run after simulation (e.g. an animation setup) or that it is a function that prompts for arguments before running (e.g. a design optimization). You also have to ensure that neither the name of the model nor the replaceable contents is hard-coded into the command.
• The last day of the current support period is shown in the Help/About dialog.
• Variable legend in the plot window may be written using extended character sets (UNICODE).
• Future change: Sqrt and abs/sign will be reworked such that sqrt(-1e-16) generates an error (instead of zero), and abs does not generate events. If the old behaviour for sqrt was desired replace sqrt(x) by sqrt(max(0,x)). Library developers can already activate this using

  Advanced.GuardedSqrt=true;
  Advanced.AbsSignEvent=false;
  

• Possible to use DDE-coupling for all solvers. This requires additional files (please contact Dynasim for more information).

News in version 6.0c

• Updated distribution so that Dymola and libraries can be distributed on a single CD. Installation of Dymola and associated libraries is then done in one sequence from a single CD. The Dymola installation directory is automatically used for installing libraries; the user need only click on the Next and Finish buttons. Dymola is started after the complete installation, including libraries.

News in version 6.0b

• Added highlighting in the diagram layer to visualize model structure.

  Replaceable and redeclared components:

  Highlights components and connectors which can be replaced. Replaceable components with the default value are shown sunken, as a socket. Redeclared components are shown raised, as mounted in the socket. Components of a replaceable class are outlined with a dashed line.

  Inherited components: (off by default)

  Highlights components and connections inherited from a base class with gray background color. Such components cannot be deleted, moved or replaced.

  Highlighting can be turned on or off in Edit/Options, for example when copying to clipboard or exporting images. It is always off during File/Export/HTML.
  Redeclared components are always shown. The context menu command "Show Redeclared" has been removed.

• Components of a non-existing class are marked with a big red cross in the graphical editor. This makes it easier to find model inconsistencies.
• Replaceable classes are shown in the component browser. Redeclared classes are highlighted as in the diagram layer (raised or sunken).

• Selection of iteration variables based on a confidence number for guess values. Currently enabled by setting Advanced.UseConfidenceNumberForStartValues=true.

  The initialization problem involves often nonlinear algebraic loops. When solving a nonlinear system of equations, it is important  that the iteration variables have good start values to guarantee convergence and as well as convergence to the desired solution in case the nonlinear problem has several solutions. Dymola decreases the size of a nonlinear system by eliminating variables by tearing. It is then a good idea to eliminate variables without start values or variables having less confident start values and keep as iteration variables those variables having more confident start values. Dymola now introduces a natural way to estimate the confidence of start values.

  Models are typically built by composing components. The components may include settings for start values. If the top model sets parameters or start values of the components, the idea is to improve the model, not make it worse. When building the model we ought to have better and more specific information than when the models were built. Thus it is reasonable to have more confidence in start values being set from higher hierarchical levels of the model. This approach gives both the model developers and the users good control possibilities. Changing a start value is expected to have immediate effect.

  A model has a hierarchical component structure. Each component of a model can be given a unique model component hierarchy level number. The top level model has a level number of 1. The level number increases by 1 for each level down in the model component hierarchy. The model component hierarchy level number is used to give start values a confidence number, where a lower number means that the start value is more confident.  Loosely, if the start value is set or modified on level i then the confidence number is i. If a start value is set by a possibly hierarchical modifier at the top level, then this start value has the highest confidence, namely 1 irrespectively on what level, the variable itself is declared.

• The encryption feature has been extended with features for hiding documentation of classes and license check for sub-packages. The new encrypted files can only be opened in Dymola 6.0b and later. If you want to create encrypted files compatible with earlier versions of Dymola, please contact Dynasim.
  Details:
  • Inside Protection there are new annotations showDocumentation and nestedShowDocumentation to control if the documentation layer is shown.
  • Inside Protection there is a Library entry of the form Library="LicenseOption" or Library={"LicenseOption1","LicenseOption2"}. This can be applied to any class, and if the license check fails the class is completely removed (any cannot be used internally in the library). To be future compatible any other Library-annotation is treated as a failed license check. This annotation is also preserved with Encrypt total model
  • If the encrypted class is hidden from browser or from documentation layer it is for HTML-generation (before encryption) treated as a protected class.
• The logic for continue has been revised to avoid running model code that takes time and might fail.
  An issue is models using C-functions to opening external files with "when initial()", i.e. functions other than the table-function used in Modelica that are used in the same way. These will not be run during "continue". Either change to use ExternalObjects or contact Dynasim for compatibility changes.
• Dymola on Linux: The portability of Dymola to various Linux distributions has been improved. The changes may affect the installation of Dymola.

  Previously Dymola was a statically linked application, which means that the application contained all runtime libraries. This caused problems on some Linux distributions because of subtle incompatibilities between the C runtime library and the operating system. Starting with Dymola 6.0b on Linux, the executable program is dynamically linked to the most basic runtime libraries. This means that the native library of the Linux distribution is used, avoiding any incompatibility with the operating system.

  With dynamic linking there is a small risk that some of the native dynamic libraries are incompatible with the Dymola application. To resolve this problem, the Dymola distribution for Linux contains a set of known compatible dynamic libraries. These libraries are not normally used, but are available to resolve any compatibility problems. Install Dymola as follows:

  1. Install the Dymola distribution from the tar-file. Copy the license file to dymola/insert/dymola.lic.
  2. Set the environment variable DYMOLA to point to the Dymola root directory.
  3. Start dymola/bin/dymola6. If the program starts you are done installing Dymola.
  4. If there are any problems with dynamic libraries you will get error messages from the dynamic loader (ld.so). Run the script dymola/bin/dymola.run, which sets up the environment variable LD_LIBRARY_PATH and then runs Dymola. If the program starts you are done installing Dymola.
  5. If the problems persist, copy dynamic libraries from dymola/bin/libs/old to dymola/bin/libs as needed and try again with Step 4. This may require some trial-and-error experiments until a running configuration has been found.
  If any problems arise, please contact support@dynasim.se.

  Dymola 6.0b is generated on Red Hat Linux release 7.1; earlier versions supported by Dymola 5.x are not supported any more.

News in version 6.0a

• Support for Visual Studio 2005.
  If you link with your own C-libraries you have to recompile them as multi-threaded. The reason is that single-threaded compilation is phased out in Visual Studio 2005, and multi- and single-threaded libraries reading from files are not link-compatible. Thus Dymola only supports linking with multi-threaded libraries.
• Support for Matlab 7.2.
• Improved check of connections. The improvements imply that:
  • If a model singularity is likely caused by incorrect/missing connections no additional diagnostics is given.
  • Diagnostics for connection sets with multiple sources for the same causal signal, or no source for a causal signal.
    Note: In some models, the missing equation for the input is provided textually. Please change these models to use source-blocks instead.
• Improved animation window.
  • Slider and time input field for quickly setting current time for animation.
  • Possible to animate several result files together in the same window using the context menu in the plot-selector (Animate together for result file).
  • Context menu in animation allows operation on the currently selected object:

• Correct default values are now presented in the parameter dialog also when modified in extends clauses. The "View Parameter Settings" include the value from the input field.
• Default values for function inputs may depend on package constants and other inputs, e.g.

    function vectorAdd
      input Real x[:];
      input Real y[:]=x;
    ...
  

  If y is not specified the default is that x and y are the same. Note: This is especially important for automatically constructed record-constructors.
• Renaming classes (using package context-menu Edit/Rename) automatically update all references in all loaded classes to reflect the name-change. There is no undo command for this.
  Please contact Dynasim if you need more information, or also want this behaviour when renaming components.
• The info-layer now supports anchors with normal html-syntax. Hyperlinks using fragments #diagram, #text, #info and #icon link to the corresponding layer. All other anchors are assumed to refer to anchors in the info-layer.
  Note: When generating HTML documentation, several classes may be included in one file; the anchors should thus be unique independent of the class.
• Implemented transparency for File/Export/Image, which creates an image with transparent background if you set Advanced.TransparentImageBackground=true. This flag will give you objects which are separated from the background, with the same color as on the screen (only the background is transparent).
• Setting Advanced.TransparentImageObjects=true allows export of image with transparent objects, not only transparent background. Transparent objects will be exported as transparent in the image. The possible drawback is that colors can be changed depending on the background when the image is inserted into a document.
• Heading and axis titles of the plot window may be written using extended character sets (UNICODE).
• File/Export/Animation creates AVI-files with higher quality by default. File size increases slightly.
• If the simulation log is bigger than 10 MB, only a pointer to the log file is printed in the log window after a simulation. If the file is smaller the contents is shown in the log window (as before).

News in version 6.0

• Dymola 6 includes new features to perform integrated experiments with Modelica models
  1. Model calibration and assessment:
     • Tuning of model parameters to get good agreement with measured data.
     • Analysing parameter sensitivities and dependencies.
     • Checking if parameters can be tuned from the measured data.
  2. Design optimization
     • Tuning of model parameters to improve system behavior by multi-criteria.
     • Optimization based on simulation runs.
  3. Data preprocessing
     • Detrending, elimination of outliers
     • Analyzing and eliminating noise
  4. Experimentation
     • Parameter perturbations
     • Parameter sweeping
     • Monte Carlo studies
  5. Visualize 3D
     • Data visualization in 3D
     • Rendering of 3D scenes
     • Surface plots
     • Bar graphs, pie charts
  6. Model management
     • Version management
     • Model dependencies
     • Encryption of models
  7. Modelica data structures and GUI
     • Building customized parameter and function dialogs
  These features in Dymola 6 are described in more detail in the document Dymola 6 Additions.
• Other new features are described as part of recent features in Dymola 6 Additions:
  • Package browser: Functions and records as default get an icon in the browser similar to the icons used in the Modelica 2 library. This makes it easier to find functions and records in the browser.
  • The parameter dialog will automatically get a scrollbar even for the non-default group, see section 'Graphical editor/Parameter dialog'.
  • Graphical objects can be aligned, as an alternative to moving the objects. See section 'Graphical editor/Edit align' and following sections
  • Further improvements for replaceable components when 'Show instantiated' is active: the text and documentation layers show the text of the redeclared class.
  • Further improved HTML generation and documentation layer. See section 'Graphical editor/HTML documentation'.
  • Improvements for replaceable components: Possible to change class using the context menu for the component, and the parameter dialog shows the parameter dialog of the redeclared class (even when 'Show instantiated' is off). See section 'Graphical editing/Replaceable components'.
  • New Dymola command window with package browser, see section 'Simulation/Simulation windows'.
  • The menu command 'Windows/Tools' makes it easy to select which toolbars and browsers will be visible, see section 'Simulation/Simulation windows'.
  • Save settings of 'Position and geometry of Dymola window', now also includes 'Show instantiated', and layout of multiple Dymola windows including the new command window.
  • Easy addition and modification of variable declaration in a model using 'Edit/Variables'. See section 'Modelica text editor/Variable declarations'.
  • The menu command 'Commands/Add command' can specify that commands are part of check, and check has been extended. See section 'Simulation/Commands menu'.
  • Improved support for simulation robustness and debugging:
    • New one-step solvers, see section 'Simulation/New Integration algorithms'.
    • Tooltips and links in simulation log, see section 'Simulation/Direct link in error log to variables in model window'.
    • Function handling has been redesigned. The user benefits are:
      • Can differentiate functions to generate symbolic Jacobians, see section 'Simulation/Analytic Jacobians'.
      • Inlined/evaluated functions are not included. This avoids warnings for array of records and allows use of evaluated functions for realtime simulation.
    • The variable browser using 'v=' contains only the variables for which it makes sense to set guess values. See section 'Simulation/Discriminating start values'.
    • The simulation log contains information on potential problems such as chattering when the simulation is stopped or completed. See section 'Simulation/Extended diagnostics for stuck simulation'.
    • Setup for finding min/max violations, see section 'Simulation/Bounds checking for variables'.
    • Function call as context for errors in user-written functions; see section 'Simulation/Traceback message for errors in functions'.
    • Online parameter changes are stored in dsfinal.txt
    • Pressing 'Stop' will automatically terminate the simulation process, if dymosim does not respond to normal stop'. See section 'Simulation/Ensuring that ‘Stop’ stops the simulation'.
  • Plot window: it is possible to set resolution for high-resolution printing or export to clipboard. See section 'Plotting and animation/Other plotting'.
  • Direct manipulation of the view in the animation window using the mouse, see section 'Plotting and animation/Animation'.
  • Support for compiling models with dSPACE release 4.2, see section 'Matlab and Simulink'.
  • Possible to install dymola in 'Program files', and default start-directory is 'My documents/Dymola'. Please note that this cannot be an UNC-path (i.e. \\server\...). See section 'Installation and setup of Dymola'.
  • Redesigned compiler setup, see section 'Initialization and setup'.
  • Added library Modelica_LinearSystems, see section 'Libraries/Other libraries'.
• Modernized look-and-feel of Dymola 6 when running on Windows XP which makes the user interface easier to navigate. In particular the package, component and variable browsers are more visible and the modeling/simulation mode is more clearly indicated.

News in version 5.1 to 5.3e