and 
buttons, you can use tabs for each page, or a dropdown list including all pages. This is applicable to graphs, tables, group inputs, and arrayed inputs, and is selectable from the properties panel for each. See Pages Styles for details.These release notes list feature changes for the current release of Stella Architect, iThink Version 1.4, Stella Professional, and Stella Designer. Feature changes are also shown for previous versions of the software. There is a list of Known Issues for the current software release as well as a version by version detailing of Defects Fixed.
You can now use keyboard shortcuts to select tools when building models. See Select Stock and so on in Keyboard Shortcuts for details.
You can now rename the graph and table pads that show when the graph or table is minimized. Editing works just as it does for variable names.
You can now use the annotation button to display a variable's documentation, equations and units of measure. See Annotation Button (Interface) for more details.
The units of measure now appear in the graphical panel - making it easier to there are units issues with graphical functions. Also, if the equation for a graphical has an error the panel will open on the equation instead of the graph.
When setting interface page size, existing content may restrict how much it can be adjusted. If a page has content that would be outside the page on resizing you will not get a message indicating the reason the page size was not able to be changed as requested.
A new Loop Label object has been added to the mode editing toolbar. This allows you to label loops and will highlight the links in the loop when the mouse passes over it. See Loop Labels (Model) for more information.
A new navigation button has been added to the model to allow position changes to predefined locations or variables. These can be useful as shorcuts for navigating through large models. See Navigation Button (Model) for more details.
Use NAN to set a variable value so it will not appear on graphs. Use CLOCKTIME to return the current time on the computer the software is running on.
There is now an option to fit the graphics content to the frame. See Graphics Properties for more detail.
In addition to publishing model interfaces, you can now create multiplayer games in which players connect from their own browsers, make decisions, and indicate their readiness to proceed. The model then uses decisions from all of the players as inputs for the next step in the game. Multiplayer games can be published to the isee Exchange under the Creative Commons license, with some limitations on model size. See Multiplayer Games for more details.
It is now possible to create sophisticated animations based on SVG graphics files. These animations can include color, size, and rotation. See Animation Object(Interface) for more details.
When you add a button to your interface, you can now set conditions under which each of the actions will be executed. This is especially useful in multiplayer games. See Button (Interface) for more detail.
Published interfaces can now be made resizable, allowing them to work well on a variety of devices. For details, see Resizable Interfaces.
You can now collect data on the use of your published simulation, including the results from different users and the time spent on different pages. Data collection is available through an isee Exchange subscription. There are several reporting options available for analyzing the data. For more details, see Data Collection.
The modeling language has been extended to allow the use of expressions inside of the array functions (such as SUM(a*b)) to take an inner product. An inner product operator has also been added for 1 and 2 dimensional arrays. See Working with Arrays and especially Specialized Array Manipulation for more discussion.
There are new options for navigating through multiple pages of graphs, tables, and input devices. Rather than the standard and buttons, you can use tabs for each page, or a dropdown list including all pages. This is applicable to graphs, tables, group inputs, and arrayed inputs, and is selectable from the properties panel for each. See Pages Styles for details.
When you connect a variable to a module, or a module to a variable, you will see a menu item allowing you to select which variable within the module to connect. This will appear only if there is something marked as an input or output within the module that has not yet been connected.
We have made a behavior change when you are using a separate initialization equation for a graphical function variable. Previously, the I equation would determine the value of the variable. Now the I equation determines the input into the graphical function.
Graphs will now use the initial values computed in the background. For bar graphs and pie charts, this means they will be populated with initial values before and after running an output restore. Regular graphs will not draw, but they will have a scale. This is true for models and interfaces, including published interfaces. Note that changing a controlled value will no longer generate a new initialization. See known issues for more discussion.
We have adjusted Stella Live to be less sluggish on larger models, and also to give visual cues when the model is in the process of computing. In particular, as you dial a knob, while the software is computing the graphs, over model elements will be displayed in gray instead of red. This indicates that the graphs are potentially out of date relative to the value showing for the knob.
In Earlier Versions
You can now edit and work with your models online by logging in through the isee Exchange. See Stella Online for more details.
Available for both the model and interface, we've added two new options for displaying results. The Pie Chart is a new output format for the display of variable values at a point in time. The Area Graph allows you to display a series of graph values stacked on one another, with distance between them based on the values of the variables. Both of these are configurations of graph objects and can be selected in the Graph Properties Panel.
The new Allocation Input (Interface) object allows users to set values for inputs that need to add up to a set amount. It's implemented as a draggable pie chart, with adjacency determining the sequence in which other inputs change as the user makes adjustments.
A reset button (
) has been added to interface input objects, allowing them to be reset to the model value by the user (the button also marks the control as changed). The option to use this is set in the Interface Settings Properties Panel.
Buttons on the interface can now execute either an import or an export of an on demand data link. These actions do not do anything for published models. See Button (Interface) for more details.
Graphical input objects on the interface can now be changed either by tracing the shape, or by switching the Table view and entering xy pairs. See Graphical input (Interface) for more discussion.
You can now import both the x and y axis for graphicals by putting :x and :y after the name of the graphical in successive rows or columns. See Creating Import and Export Files for details. The import options now handle arrayed inputs more consistently and better manage compatibility between US and European number formatting.
The Parameter Control Panel now highlights variables that have been overridden on the panel, making it clearer what has been changed (this is especially important for values already imported).
Any graphical functions that use a constant as an input will now be marked as invalid. This makes it easier to uncover issues where TIME might have been the intended input. If you do want a constant as an input, you can use an expression (as in 0+0) to prevent the error.
The INIT and ENDVAL builtins can now take an expression in addition to using a variable directly.
You can now control the colors and line styles for the different lines appearing in comparative graphs. This is set for each model (and there is a default setting for new models).
Window positions are now preserved for all dialog boxes and panels, making it easier to get back to the same setup you've been working with.
By right clicking on a graph, table, or numeric display (or any interface control with a variable in it), you can jump to the definition of that variable in the model (not available for Stella Designer).
You can now format multiple items on a graph or table using the right click menu.
You can now preserve graphs and tables with a single click so that they won't change with new runs or be cleared when you restore outputs. This is done from the Graph Properties Panel.
We've added the functionality 'import runs from external data sources' to the Data Manager. This makes it easy to compare results with measured data or with results from other models.
A number of other improvements have been made to the Data Manager, giving you more control over the way in which runs roll off the list and what runs are displayed in graphs and tables.
The import and export dialogs have been improved to make it both easier and clearer to set up imports and exports. The use of temporary imports has been reintegrated into the import dialog so that everything is in one place.
The parameter control window has been enhanced so you can see the original model value, and to make it easier to reset and control different variables.
Any variables appearing in the parameter control window are also marked on the model diagram (
).
The simulation speed slider has been replaced with a field that allows you to input how many seconds you would like the simulation to take.
A speedometer style gauge has been added to the interface to allow you more variety in presenting results.
Spatial map has been integrated into the interface, making it easy to present spatial information in an appealing manner.
An Array input device has been added to allow sequences of array values to be input into the interface.
Explore mode on the interface has been replaced with Experiment Mode, which behaves the same way as Presentation mode does, making it easier to test your interface.
There is now a button action to reset a variable to its equation (or imported) value.
The switch object can now be configured to appear as a checkbox.
You can now optionally animate diagrams shown in the Model View, including those shown for storytelling.
The Model View controls have been improved to make it easier to include model elements on interface pages and stories.
The Pages Panel(Interface) can now be collapsed to allow you more room for editing.
Before running, control changes will update model values including numeric displays, speedometers, and spatial maps, allowing users to see the initial conditions that will be used as they set things up.
Sketchable graphs update automatically in Stella Live.
Stella Live executes more quickly during development and on published sims.
Embedded images display more quickly.
The thumbnail drawing is much faster.
Divide by 0 errors are now reported on the interface.
Models are continuously reinitialized as they're built so that you can see the effects of equation changes immediately by hovering over a variable.
There is also an option to perform a new simulation each time you change model structure, which allows you to see the effects of changing connections and equations immediately.
Circularity checking and reporting have been improved and now detect subtle initialization dependencies related to leakages and discrete stock equilibrium initializations.
Circularities are now reported one loop at a time, and all the variables in the loop are marked invalid, making it easier to visual the loop.
Non-stock equations can now specify an initial value to be used when the model stocks are initialized. This is very helpful for breaking initialization circularities that have been identified.
We have added a // operator which works the same as SAFEDIV, giving 0 instead of an error when dividing by 0.
Divide by zeros are more accurately reported, even when they occur within expressions such as MIN. Legacy models will automatically have some of this reporting masked to maintain compatibility.
Checking Unit Consistency now reports where in equations unit inconsistencies are detected.
For locations that use a , as a decimal separator, you can now enter equations using this, as well as ; as an argument separator. This can be turned on and off in the Preferences Dialog.
The registration dialog behavior has been changed so that clicking twice on the button to open a web page does not cause two or more activation requests to be sent to our server.
Sliders and Numeric Inputs now allow you to specify the width of the slider or input box in order to get better horizontal alignment when placing one object below another.
Sliders, Numeric Inputs, Knobs and Switches on the interface now have an option to wrap text.
The Causal Lens now highlights the path of selections you have made to make it easier to see the sequence of causality.
The interface development tools are all new. The new interface development and deployment capabilities take you from design to presentation and, optionally, the web, quickly and cleanly. See Building Interfaces for more detail.
Interfaces developed in previous versions of the software will be translated, and most of their functionality retained, though some adjustment will be necessary to get optimal results. See the notes on Using Version 10 Models for more comments on interface translation.
Version 1.1 adds a number of new and updated panels that can be used to analyze and navigate your model.
The Causal Lens™ displays graphs for a variable and the inputs to that variable, helping you to better understand the sources of model behavior.
The Results Panel now includes both a graph and a table, allowing you to easily look at specific values at specific times. There's also a checkbox to not round the scales, which is helpful when looking at variables with limited movement through a simulation.
The Simulation Log records any variables that go above or below their specified ranges, as well as graphicals with inputs above or below their specified minimum and maximum x values. The same log is also used to report messages about anything that happens when opening a model.
The Parameter Control Panel allows you to see what variables are changed relative to their model equations, and also make changes to those variables.
The Selection History panel keeps track of which variables you've selected, making it easier to go back and see where you've been. Click on an entry to take you back to that variable.
We've improved selection highlighting to make it easier to see which variables have been highlighted. This is especially useful as we've added a number of new ways to navigate between variables.
You can right-click on a variable in an equation and jump to that variable. There's also a Causes/Uses menu to navigate to variables that cause, or are used by, the variable you're looking at. See the discussion on the Equation Tab of the Properties panel for more details.
We've improved the error message reporting in equations, and made this reporting somewhat stricter, especially around the MIN and MAX functions, to prevent ambiguity.
The units messages now tell you how many variables you have left to define units for. If you haven't defined units for any variable, the dropdown simply reads Define Units.
There are no longer any restrictions on what names you use for variables, except that they must be unique and not conflict with any Builtins. When used in equations, variables that have operators or other characters will be quoted and escaped. (If you type them in, you'll need to do this yourself, but it happens automatically if you choose them or use autocomplete.) Variables with a period (.) in them will also be quoted when displayed on the diagram (this is to prevent confusion with module qualified names).
Models open significantly more quickly than before, letting you get on with development. Exporting of data is significantly faster and will happen in parallel during simulations.
An analog to the SUM function takes the product across elements of an array.
An option has been added to the Preferences Dialog that turns off Stella Live when in Explore mode. This allows you to work with larger models and make changes on the model window, but only simulate them when you explicitly request a run.
You no longer need to go to the home module to change run specs or other model wide settings. These are available in the panel from any module.
You can now order equations by sector, and also view values in the Equation Viewer. Complete information about model size has also been added to the end of the equation listing
We've redone what used to be called Posters or Simulation Messages into an easier to use system of Simulation Events that can be applied separately to the model and interface. Existing models will have these converted to the new format when opened with the new products. Navigation events will need to be redone - see Simulation Events.
We've added new export formats to export a single value or set of values at a time, and improved the way tables are specified for exporting - see Export Data dialog box
The registration dialog behavior has been changed so that clicking twice on the button to open a web page does not cause two or more activation requests to be sent to our server.
Sliders and Numeric Inputs now allow you to specify the width of the slider or input box in order to get better horizontal alignment when placing one object below another.
Sliders, Numeric Inputs, Knobs and Switches on the interface now have an option to wrap text.
The Causal Lens now highlights the path of selections you have made to make it easier to see the sequence of causality.
The interface development tools are all new. The new interface development and deployment capabilities take you from design to presentation and, optionally, the web, quickly and cleanly. See Building Interfaces for more detail.
Interfaces developed in previous versions of the software will be translated, and most of their functionality retained, though some adjustment will be necessary to get optimal results. See the notes on Using Version 10 Models for more comments on interface translation.
Version 1.1 adds a number of new and updated panels that can be used to analyze and navigate your model.
The Causal Lens™ displays graphs for a variable and the inputs to that variable, helping you to better understand the sources of model behavior.
The Results Panel now includes both a graph and a table, allowing you to easily look at specific values at specific times. There's also a checkbox to not round the scales, which is helpful when looking at variables with limited movement through a simulation.
The Simulation Log records any variables that go above or below their specified ranges, as well as graphicals with inputs above or below their specified minimum and maximum x values. The same log is also used to report messages about anything that happens when opening a model.
The Parameter Control Panel allows you to see what variables are changed relative to their model equations, and also make changes to those variables.
The Selection History panel keeps track of which variables you've selected, making it easier to go back and see where you've been. Click on an entry to take you back to that variable.
We've improved selection highlighting to make it easier to see which variables have been highlighted. This is especially useful as we've added a number of new ways to navigate between variables.
You can right-click on a variable in an equation and jump to that variable. There's also a Causes/Uses menu to navigate to variables that cause, or are used by, the variable you're looking at. See the discussion on the Equation Tab of the Properties panel for more details.
We've improved the error message reporting in equations, and made this reporting somewhat stricter, especially around the MIN and MAX functions, to prevent ambiguity.
The units messages now tell you how many variables you have left to define units for. If you haven't defined units for any variable, the dropdown simply reads Define Units.
There are no longer any restrictions on what names you use for variables, except that they must be unique and not conflict with any Builtins. When used in equations, variables that have operators or other characters will be quoted and escaped. (If you type them in, you'll need to do this yourself, but it happens automatically if you choose them or use autocomplete.) Variables with a period (.) in them will also be quoted when displayed on the diagram (this is to prevent confusion with module qualified names).
Models open significantly more quickly than before, letting you get on with development. Exporting of data is significantly faster and will happen in parallel during simulations.
An analog to the SUM function takes the product across elements of an array.
An option has been added to the Preferences Dialog that turns off Stella Live when in Explore mode. This allows you to work with larger models and make changes on the model window, but only simulate them when you explicitly request a run.
You no longer need to go to the home module to change run specs or other model wide settings. These are available in the panel from any module.
You can now order equations by sector, and also view values in the Equation Viewer. Complete information about model size has also been added to the end of the equation listing
We've redone what used to be called Posters or Simulation Messages into an easier to use system of Simulation Events that can be applied separately to the model and interface. Existing models will have these converted to the new format when opened with the new products. Navigation events will need to be redone - see Simulation Events.
We've added new export formats to export a single value or set of values at a time, and improved the way tables are specified for exporting - see Export Data dialog box
Version 1.0.3 is designed to work well with high resolution displays, including Retina displays on Mac. The icons on the screen will automatically be enlarged to accommodate displays with high pixel counts, and the diagrams will be presented so that they're easy to read at default zoom levels.
We've updated the icons used throughout to be clearer and more consistent, in addition to working better on different resolution monitors.
The movement back and forth between Edit and Explore modes has been streamlined. Changes you make to constants in Explore mode, by adjusting knobs or entering values in the Results Panel, will persist if you enter Edit Mode and then go back to Explore Mode. Modifying an equation will reset any value you set in explore mode, but only for that equation.
You can set values for arrayed constants in the Results Panel in Explore mode (arrayed constants don't have adjustable knobs). Just open the results panel and click on the constant you want to change. You can select the array entry to change from the dropdown at the top of the results panel.
Constants now have an increment setting that can be used to control the number of values they'll take on when changed via a knob in Explore Mode. This can be very helpful if you want to limit the number of values that a constant can take on, and will even allow for the addition of switches that take on only 0 and 1 as values. The increment is set in the Scales and Ranges panel.
This functionality has been moved to the Panel to make it easier to use. Rather than opening the import dialog, open the Properties Panel on the model and there's a new tab 
, to make temporary changes, including importing interface settings from STELLA and iThink Version 10.1.2 models.
Clicking on the add variable 
button in the graph and table panels will now open up the Find dialog, making it easier to select and add variables.
Copying model diagrams into the clipboard is now more sensitive to context, and will remove the borders from graphs when they're copied by themselves. This makes it easier to paste your content into other applications.
Now when opening a saved model, it will open in the same view in which it was saved.
Substantial improvements have been made to Stella Professional's computation engine. Not only will models open more quickly, but large models should simulate three to eight times faster than in the previous version. This allows you to get more done more quickly.
A new function, SAFEDIV(<numerator>, <denominator>, [<onzero>]), has been added, which allows division in cases where the denominator might become 0. When this happens, the function will return 0, or the optionally specified third argument. Use this to prevent simulations stopping because of a divide-by-zero condition.
The Import functionality has been enhanced to allow you to import values without making any changes to model structure. This is useful for running experiments in which you don't want to change the model, but just see the results of changing constants and graphical functions. This also allows you to override computed variables with a constant value, much like you would when, for example, attaching a slider to a converter on an interface.
An option has also been added to the Import dialog that will read interface control values from a model created in version 10.1, and create a temporary change file. This allows you to simulate models in Stella Professional and get the same results that they generated in the Version 10 products.
The Alt key now works by holding it down, rather than tapping it, when you want to repeat a build step, such as drawing connectors between variables.
When you position the mouse over a connector handle (or arrowhead), the color of the connector will change, to indicate that it's active and can be dragged. Similarly, when you position the mouse over a variable name, the name will be highlighted with a box to indicate it can be repositioned. This makes it much easier to adjust model layout, especially for densely connected models.
A Windows menu has been added to allow you to more easily navigate between models when you have multiple models open. Under the Windows menu is an item to open the Results Panel. A Run Specs menu item has been added to the Model menu, as an alternative way of opening the Run Specs panel.
Registration information can now be accessed and changed through the Registration dialog box opened from the Help menu. This allows you to change your registration information and unregister the software from one computer, so you may use it on another.
When you place a connector, the style panel will contain an option for a Delay Mark. See Styles Tab for more details. The polarity markers can be shown using either +/- or s/o, as specified in the Model Settings Properties Panel
Set this on the Model Settings Properties Panel to shorten the names displayed in graphs and tables (e.g., have profit be displayed instead of accounting.profit).
You can now create a Sketchable graph for any graphical function in the model, without needing to add another variable for comparison. This allows you to use the Sketchable graph as an input control. See Sketchables for more information.