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Posts Tagged ‘Version 9.1.2’

LOOKUP Built-in Allows Reuse of Graphical Function Curves

Sometimes it is necessary to access a data set from multiple places within a model.  For example, a manufacturer may have a non-linear curve that maps capacity required for a given product to raw material required to manufacture it.  Such a curve is shown below:

If one production line needs to know this information, a graphical function works fine.  However, if there are two production lines in the model, the second line also needs this information.  If the two lines are identical in structure, the model could be arrayed to share the curve for both lines.  If they are not, it was necessary in versions prior to 9.1 to make a copy of this curve for the second production line.  Then if, at a later time, one copy of the curve needed to be changed, the other one also needed to be changed in the same way.

Version 9.1 introduced the LOOKUP built-in.  This allows any graphical function curve to be re-used as many times as desired within the same model.  Note that a graphical function, by definition, ties a specific equation to the given curve.  Using LOOKUP, it is now possible to evaluate that same curve using several different equations in the same time step.

In this case, let’s assume the second production line has similar variables with “2” appended to their names.  Thus, there is a capacity2 and a material needed 2.  Prior to version 9.1, it was necessary for material needed 2 to be an identical copy of material needed.
Since version 9.1 allows the curve to be re-evaluated for any arbitrary
expression, material needed 2 no longer needs to be a graphical function.

material_needed_2 = LOOKUP(material_needed, capacity_2)

This equation simply evaluates the graphical function stored in material needed using capacity 2 as the x-coordinat

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LOOKUPXY Built-in Increases Dataset Flexibility

March 3rd, 2009 1 comment

Version 9.1.2 adds the ability to incorporate non-regularly sampled data easily into your models.  Many people use the graphical function for historical records of data.  The graphical function, however, assumes a fixed interval along the x-axis.  This can make it difficult to use data like the following:

Day Flow
1 12.1
3 7.6
4 15.2
6 13.5
9 23.8
12 17.3

While it is easy to determine the fixed interval to use to capture all of these points (1 day), it is more difficult to determine what data points to use for the missing intermediate 1-day values.  There are also many cases where it is very difficult to find a fixed interval that works for a given dataset.

Graphical Function Day (click for full size)

The LOOKUPXY built-in was specifically added to address this issue.  It is unique in that it requires two separate graphical functions:  one for the x-coordinates of each pair and one for the y-coordinates of each pair.  The number of points in each graphical function should match; if they do not, extraneous points are ignored.  The data values (x-coordinates and y-coordinates) are both entered by the user as the y-values in each graphical function.  The x-values in each graphical function are ignored; only the number of points matter.  It is a good idea, though, to run the x-axis of both from one to the number of points.  That way, it is easy to verify that the values in each graphical function properly align with one another.  In addition, the x-coordinates should be in increasing order.  If they are not, however, the program will automatically readjust them when the model is first run.

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A Better Chained Slider

Chained slider in iThink 9.1.2

The chained slider has always been a useful interface object in iThink and STELLA for allocating 100% of something to different variables within a model.  For example, you may want to build a dashboard where someone could play around with allocating funds to various programs within the Obama Administration’s economic stimulus package.

In iThink and STELLA version 9.1.2, we decided to improve the behavior of the chained slider in response to feedback we’ve received from customers.  We also wanted to nail down the behavior before we added support for it in models published to the web with isee NetSim.

Categories: STELLA & iThink Tags:

New ARRAYRANK Builtin Sorts Array Values

Version 9.1.2 will introduce the ARRAYRANK feature.  Here is a preview of its capabilities.

The ARRAYRANK built-in can be very powerful for some applications.  It allows you to order the values in an array from smallest to largest or vice-versa.  In this sense, it expands upon what ARRAYMINIDX (find the index of the smallest value) and ARRAYMAXIDX (find the index of the largest value) already do.

To introduce ARRAYRANK, let’s look at a simple model that uses it.  In this model, we explore the efficacy of applying tiered commissions for salespeople in an effort to encourage them to sell more.  Each tier is designed as a reward so the top seller in any given week gets the highest percentage, while those who do not perform will get the lowest.  The tiers are:

Top seller:                    20%
2nd best seller:            15%
3rd best seller:             10%
Everyone else:               5%

Note that the non-tiered system gave everyone 10%.  The model is very simple:

Categories: STELLA & iThink Tags:

What’s New in isee NetSim 1.0.1

Typically when software moves from version 1.0 to 1.0.1, the minor release mostly consists of bug fixes.  I’m happy to say that isee NetSim 1.0.1 is not all about bug fixes, (though we have fixed a lot of issues and increased performance).  This release includes some cool new features too:

Chained Sliders are now supported

Not only did we add the chained sliders to isee NetSim, we improved the behavior and also added some functionality you can use in iThink and STELLA 9.1.2 and isee NetSim.  We have dedicated a separate post to the details and published a NetSim so you can try it out online.

Page size dialog (click to expand)

Custom Page Sizes

In addition to the fixed screen resolution page sizes, you can now specify a custom page size by choosing the “Other” option.

The fixed options (640×480, 800×600, etc.), represent the target screen resolutions of the computer screens that will be displaying the model.  This is a great option for sizing pages of models distributed with the isee Runtime.  Runtime models are run from a CD-ROM or installed on the users hard drive and these options are great because you know the model will work for the screen size you choose.

Publishing to the web is a different story.  The model runs in a web browser.  Different browsers have different amounts of available display space.  Users may have add-on toolbars that take up more of that space.  They may be running at different screen resolutions too.

With the new custom size option you can configure a page size that works best for your model when running on the web with isee NetSim.  We have found that making the pages wider and making use of horizontal space is a good strategy for publishing to the web.

Print Graphs

Did you notice the little printer icon on the graph? (Well, you can’t see one here — but open up a sample NetSim and you will) Click on the printer icon in a graph in any NetSim and you’ll get a nice print-out.  You can try it out with one of the NetSim sample models.

isee NetSim Wizard prompts for credentials

HTTP Authentication support in isee NetSim Publishing Wizard

If the isee NetSim Server is running on a secure web server, (such as an intranet or extranet that requires authentication), the isee NetSim Publishing Wizard will now prompt for the credentials.  It’ll remember the username and password if you check off the option.  Currently it supports HTTP Basic Authentication.

If you’re scratching your head here wondering what this means, then review the isee NetSim architecture below:

This means you can now allow users to publish (1), to an isee NetSim Server that has HTTP Authentication turned on (2).  Web Users (3) will be prompted by their browser for username and password when they run the NetSim online.

So if you want to secure your published models, or publish them to a secure intranet/extranet, you can with isee NetSim 1.0.1

Month names in isee NetSim

“Use month names” Option in Tables

This one is pretty self-explanatory, but worth mentioning because a lot of customers wanted this functionality added to tables in isee NetSim. Financial reports look really clean with this option enabled.

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