Time Series Mode: Viewing Sequences of Solutions

The Time Series command enables you to open a sequence of solutions. Each solution represents the change between two successive years. ViewSOL allows you to see year-on-year changes for each variable, or it will cumulate them so that you see total changes so far.

The number and names of the solution files are listed in a special file, suffixed SEQ. Usually this file will have been prepared automatically by some other GEMPACK program (but see below).

The SEQ file may contain details of a second sequence of solutions. ViewSOL refers to the first sequence as the base sequence of solutions and to the second sequence as the policy (formerly perturbed) sequence. You can also view the difference between the two solutions, either as the difference in year-on-year changes, or as the difference in cumulative changes.

Therefore, with two solution sequences you have a choice of six possible views of the results: {Base, Policy, Difference} X {Cumulative, Year-On-Year}. A label at the right of ViewSol's upper toolbar indicates which choice is active. You can:

•Left-click on this label to switch between Cumulative and Year-On-Year views.

•Right-click on this label to cycle through Base, Policy and Difference views.

You can also choose between these options with the Timeseries Show and Style menu commands.

The label at the right of ViewSol's upper toolbar displays a message like one of the following:

In these messages the first 3 letters, SEQ, mean that you are in Time Series Mode. They are followed by a digit -- the number of years. Next will appear one of 'Base', 'Pol ' or 'Diff' corresponding to Base, Policy, or Difference views of the solutions. Then, 'Cum' or 'YonY' refers to whether Cumulative or Year-on-year solutions are shown. These last two items are summarized by the Magic Letter at the end. This is B, P, or D corresponding to Base, Policy or Difference. The Magic Letter is upper case for Cumulative view, lower-case for year-on-year. The colour of the message also changes according to settings.

The Magic Letter is used in a special way by the Charter. As well, the Magic Letter is appended to the top left cell of any table you copy to the clipboard -- to help you remember which numbers you paste to Excel.

With matrix variables, unless you filter to select a particular set element, you will not be able to view several different years at once. You can still use the solution combobox on the speed bar to select a particular year. The solution combobox always refers to years by the name of the base solution file for that year, even if you are viewing the policy solution or the differences.

As usual exogenous variables are shown in red: although if Cumulative and/or Difference views are chosen, each number shown is derived from the values of a variable in two or more simulations. In these cases, a Cumulative result is deemed exogenous if the final change in the accumulated sequence is exogenous; a difference is deemed exogenous if the value from the Policy simulation is (deemed) exogenous.

In the following example b and p are the original sequence of year-on-year results for some percent-change variable. The other results (d, B, P, and D) are calculated by ViewSOL.

Sol	1	2	3	4
b	10	10	10	10
p	10	20	10	10
d	0	9.09	0	0
B	10	21	33.1	46.4
P	10	32	45.2	59.7
D	0	9.09	9.09	9.09

The cumulative results B and P are calculated simply by compounding b and p; eg,

ViewSOL attempts to detect and treat correctly ordinary-change variables (which are added, not compounded) and levels variables (not cumulated at all). For this to work, the name of each levels variable must start with the 3 characters 'lev'.

To avoid overflow problems as large percent changes are accumulated, ViewSOL truncates cumulative percentage changes so that the absolute value does not exceed one billion. Non-cumulative changes are not bracketed in this way.

Certain restrictions apply when you are in Time Series Mode (ie, viewing a sequence).

The number and names of the solution files are listed in a special file, suffixed SEQ. Usually this file will have been prepared automatically by some other GEMPACK program (such as RunDynam). You could make it yourself with a text editor. See SEQ File Format. For example, this is one way you can make ViewSOL show you the difference between two comparative static solutions. You could also make your own SEQ file to compare two forecast sequences differing only by certain parameter settings -- RunDynam does not set up this automatically for you.

With large models and long sequences, ViewSOL may have to read in a truly enormous amount of data, especially if two sequences (base and policy) are read in. It's probably best to reduce memory requirements by not reading in variables over a certain size. But even if you specify no maximum size, ViewSOL in Time Series Mode automatically filters out larger variables to keep total (all-solution) memory needs within 500 MB. In this case the limit depends on how many solutions are read in. To see larger variables, you might need to view fewer years, or view only the base solution sequence, or you could Convert the sequence of solutions into a HAR File -- which allows larger variables to be visible.

Normally another program (such as RunDynam) will speed up the file reading by pre-computing SOL and SLI files. Or you can yourself use SLOTHTA (it comes with ViewSOL) with the (secret) WSI option to produce matching SOL and SLI files.