Erlang Library for Excel

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Support FAQ

Frequently-asked support questions

Downloading and Installation

• From what website should I download Erlang Library for Excel?

  To guarantee authenticity, always download directly from the download page on the Abstract Micro Systems website.  No other website has permission to post the software on the Internet.

Erlang worksheet functions

• Can arguments to Erlang worksheet functions contain cell references?

  Yes, of course!  You use the Erlang worksheet functions in the same way that you use any of Excel's built-in functions.  So each function argument can be any worksheet expression that evaluates to a numerical value.

• Why is it allowed to have a non-integer number of servers?

  The worksheet functions in Erlang Library for Excel all have the number of servers (nsrv) as a function argument or function return value.  In all cases where nsrv is an argument, it is allowed to take non-integer values (e.g., nsrv=17.56), and if a function returns the number of servers, then it will usually return a non-integer value.
  
  Why does this make sense?  It makes sense mathematically because the underlying mathematical functions are defined for non-integer arguments.
  
  And it makes sense practically as well.  Consider, for example, the case of a call center which has 20 agents on duty during a certain half-hour period.  Because of bathroom breaks and other "shrinkage", these agents may on average only be available for 83 percent of the time.  The effective number of agents for Erlang C calculations is then 20 * 0.83, which equals 16.6 agents.  So in this case, nsrv = 16.6, a non-integer.
  
  As another example, refer to the "case study" in the help item for worksheet function ErlcNsrvFromWait().  In that example, the function ErlcNsrvFromWait() returns the value 105.6403.  In other words, the number of agents required to achieve the desired service quality is 105.6403.  Suppose again, that in this call center, agents are only available for 83 percent of the time.  Then the actual number of agents that should be scheduled during the specified period is 105.6403 divided by 0.83, or 127.277.  In other words, the actual number of agents required is between 127 and 128.

• Can I define my own worksheet functions that call the Erlang Library functions?

  Yes.  But you will need to have an understanding of Excel's macro language, Visual Basic for Applications (VBA).  You can define your own user-defined functions in any macro-enabled workbook (*.xlsm) or create your own Excel add-in (*.xlam) and place your function definitions in your add-in.  The VBA project in the the Excel workbook or add-in must set a reference to A_Erlang.xla.

Links and references

• When I open an Excel workbook I get a message about not being able to find the Erlang Library for Excel add-In.  What should I do?

  This might occur if you uninstalled Erlang Library for Excel, using Add/Remove programs, but failed to remove "Erlang Library for Excel" from Excel's internal list of add-ins.  See Uninstall for how to do this.  This might also happen if you have manually deleted the add-in A_Erlang.xla or moved it to a different folder.

• When I open my Excel workbook I get a message about broken links?  What should I do?

  Not to worry!  See the help item on broken links.

See Also

Contents    Install    Uninstall    Broken links    Erlang Calculators    Worksheet Functions Help