Author Archive

Tips, Tricks and Shortcuts for using iThink and STELLA

June 8th, 2009 3 comments

I recently saw an iThink/STELLA power user change the direction of a Flow with a simple keystroke. And I thought the only way to change a Flow direction was to delete and redraw it! This prompted me to search for other tricks about using the software that I might not be aware of. As it turns out there are quite a few! I took a stab at creating a list.

The list ranges from Paintbrush tips to keyboard shortcuts. If there are other tricks that you know about, please post a comment and share them with the rest of us!

On bended flow

Bending a flow


•  Bend a Flow — Drop a Flow and start dragging it. When you want it to change direction at a 90 degree angle, hold the shift key while you move the cursor in the direction you want the Flow to go.

• Change the Flow direction — Hold the Control key and click on the head of the arrow.

• Disconnect a Flow — Click and hold on the end of the Flow (either the arrow end or the tail end) to drag it from a Stock.

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Lake Morey – A Great Place for a Summer Workshop!

May 1st, 2009 No comments

View from Lake Morey Resort glof course

Our next Introduction to Dynamic Modeling Workshop is scheduled to be at Lake Morey Resort in Fairlee, Vermont on August 5th – 7th.  You may be wondering  “Why Lake Morey?”

For starters, the resort is located along the shores of Lake Morey, surrounded by Vermont hills in a beautiful natural setting. It has a golf course, tennis courts and lake front swimming facilities that attendees can enjoy while taking a break from the workshop.

Not only is Vermont a wonderful place to visit in the summer months, but Lake Morey is only ten miles north of the isee systems offices. We love being able to drop in on workshops that are close by or meet with customers over a beer after hours.  It gives us an opportunity to learn more about the amazing work people are doing with our software and to get their ideas for future development.  It also gives our customers a chance to get to know us and to put a face to someone they’ve been talking to over the phone or via email.

We hope to see you this summer! If there’s someone on the isee staff that you’d like to meet with, be sure to let us know.

Please give us a call at (603) 448-4990 or send an email to to check on availability. 

Imported file not found?

March 6th, 2009 2 comments

We often get calls from customers who have copied a model to another computer and then get the dreaded “…file was not found” message when they open the model.  It may be a missing picture, Excel spreadsheet or some other imported file. When copying a model from one computer to another, you may need to copy more than just the model file.  files2If your model uses other files such as graphics, sounds or spreadsheets you’ll need to package all of them with the model file.

If you have to e-mail your model to isee support, it’s good to know how to package all the necessary files so that we can recreate your setup.

Here’s a list of the files your model may need:

  • Modules (.itt files)
  • Links (Files that a local file hyperlink button points to)
  • Data (Excel and .csv files for import/export)
  • Graphics
  • Sounds
  • Movies

Locate all the associated files in the same place as your model file.

If you have a lot of associated files you can organize them into sub-folders as pictured below:

foldersThe one thing to watch out for is the situation of having one file that is accessed in more than one way.  For instance, an Excel file that is used for importing data but is also accessed via a hyperlink button.  In this case, the Excel file should not be in a sub-folder.  Instead, keep it in the same folder as the model file.

Now you can copy the folder to another computer or flash drive, or burn it to a CD.

If you are going to e-mail the folder, you might want to zip it up so you only have one file to send.

Tip: Setting up imports for 2D Graphical Functions

January 29th, 2009 8 comments

iThink and STELLA version 9.0 introduced a powerful new feature: data import and export with Excel.  Here at isee, we were excited to hear from our customers about how much they appreciated the feature and how easy it was to use.  In fact, many customers told us that it was the major reason they upgraded to version 9.0
simple import 1

Setting up a data import from Excel is pretty straight forward:  type the name of the model variable in one cell, type the value you want to import in the cell below it, (or beside it if you are using horizontal orientation):

If you are importing a time series or graphical function, you just keep listing the data points in the cells below the variable name:

simple import 2

This kind of data formatting works well since an Excel sheet is made up of columns and rows.  But how do you format data that is harder to visualize?  Things get a little tricky when you start dealing with arrayed variables.  The most complex import is a 2 dimensional array of graphical functions.  It’s actually 3 dimensions!

I’ve put together a simple example to illustrate how to do this.

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