*Posted by Ryan Roper*

We've had a number of support inquiries where users need some way of calculating period-based summary data (such as monthly or annual averages or cumulative amounts) for use in other calculations within the same model (e.g. post-processing). GoldSim's reporting periods feature is great for generating this sort of summary data with little effort on the part of the user, but these results are only intended to be viewed and not used for other subsequent calculations. If you do need to use these results for other calculations in the same model, our model library contains a number of examples that illustrate how to calculate such results manually. This blog post briefly describes some of these examples and points you to where you can find them in our library to see them in more detail.

All of the examples mentioned in this post make use of a feature
of GoldSim known as array constructors. This is a simple but powerful feature
of GoldSim that, once you understand how to use, can make your life a bit
easier when implementing fairly complex logic with arrays (i.e. vectors and
matrices). Refer to the following simple example for a description of how to
use a vector constructor to calculate monthly cumulative amounts from rate data
such as volume flow rates: Monthly Cumulative Flows. This is a good model to look at if you’re not already
familiar with array constructors. Below is a screenshot from the model showing the calculated cumulative flow of water into a reservoir in the month of June (red dashed line).

More advanced examples of how to calculate period-based results
are briefly described below:

Time Series Data Preprocessing: In this
example, a SubModel is used to generate monthly mean precipitation amounts from
a Time Series element containing rainfall rate data. The mean values are
exported from the SubModel and used as the means in a Stochastic element that
generates daily rainfall.

Monthly and Annual Summaries: In this
example, a scalar input signal is integrated over 5 years to generate monthly
sums. The results are stored in a matrix in which the rows correspond to years
and the columns correspond to months. In this format, it is a simple matter to
calculate statistics on the rows or columns using GoldSim's built-in array
functions (e.g. meanr(), meanc(), sumr(), etc).

Annual Reporting Summaries: This model
shows two examples of how a daily signal can be integrated to obtain annual
sums stored in a vector or matrix format. In one example, a scalar daily signal
is integrated (accumulated) over 5 years to generate annual sums in a vector
format. In the other example, a vector input signal is similarly integrated
over 5 years to generate annual sums in a matrix format.

Monthly Reporting Summaries: In this
example, a vector daily signal is integrated (accumulated) on a monthly basis
over 5 years to generate monthly sums (which are stored as rows in a matrix).

As always, you can learn more by referring to the GoldSim
documentation. In GoldSim, go to Help|Help Topics. In the ‘Search’ tab of the
GoldSim Help, search for ‘

*Using Array Constructor Functions*’. In the search results, look at the article called ‘*Defining Arrays in an Input Field Using Array Constructor Functions’*.
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