Based On names a previous simulation for which this new simulation is to be based on. The Constant and Lookup values from the previous simulation are used for the new simulation, and these values can be modified using the Changes files, or any interactive changes you make. If the Resume check box is On, the new simulation will start at the end of the prior simulation; otherwise it will start at the same time as the prior simulation. To make a simulation based on another simulation, the prior simulation must come from the current model. By default, the Based On item is blank, indicating that the Constant and Lookup values in the model will be used, unless overridden by a Changes files or interactive changes.
Resume, if checked, causes the simulation to take up where the simulation named in the Based On file ended. If there is no file named in Based On then Resume will be grayed. If you do resume, you will normally need to change FINAL TIME so that the resumed simulation will continue.
at time (blank for end) if filled in will cause the simulation to be resumed at a time other than the end of the Based On simulation. If you are working with a model that uses any DELAY FIXED, MATERIAL or INFORMATION this function will fail. Also, if you are simulating a model with a Save List and that Save List does not contain all the Levels in the model, this function will fail.
Load Changes from... editing box names zero or more files (separated by commas) containing changes to the values of Constants and Lookups in the model. Where you use more than one Changes file and a Constant or Lookup is changed in more than one of the Changes files, the values are taken from the last Changes file listed. Multiple Changes files are frequently used in optimization problems. The content of and syntax for this file are described later in this chapter. By default, no Changes file is named, so that the parameters from the model will be used directly. The Load Changes from... button opens a File Selection dialog that lets you select an existing changes file.
Load CIN vals as DP. The default in Vensim is to read any values from a changes file using float point accuracy. This instructs Vensim to use double precision.
Change Constants brings up a list of model Constants for you to change (see Changing Constants below).
Change Lookups brings up a list of model Lookups for you to change (see Changing Lookups below).
NOTEWhen you press the Change Constants or Change Lookups button the Load Changes from and Based on entries are read, with the Constant and Lookup changes made in them incorporated into the changes to be made during the run. You can no longer modify the Load Changes fromor Based on items. If you change your mind, click the Cancel button and start over.
Save changes as .cin File allows you to record changes you have made interactively as a .cin file (the format for .cin files is discussed further below). This can be very useful for documenting simulations, and allowing easy repetition of previous simulations with slightly changed models.
