Here we display this parameter in full format but without redundant zeros:. In the following subsections we will explain the input and output structures. All boolean fields can also be entered as string values as well. To read a symbol from a GDX file we just need to know its name in string format. Thus, the only mandatory field of the input structure is 'name'. There are several other optional fields of the input structure that give user more control over the output structure. These optional fields are as follows:. As mentioned earlier, output of the rgdx routine will be in structure form.
This structure is very similar to the input structure. To get information regarding any symbol, we always need to display its basic characteristics, such as its name, type, value, uels, form, etc. An output structure will always have these fields:. Apart from these necessary fields there are a few additional fields as well. They are as follows:. Similar to the rgdx routine, it takes a structure input and can write multiple symbols into a single GDX file with one call.
The rest of the arguments are structures, each containing data for different symbols to be written into the GDX file. The syntax for the call is:. Most of the fields of its input structures are the same as those of the rgdx output structure.
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In the example below, we use the wgdx routine to create foo. Each column of this cell array can contain string or double or both. Again we can make use of a handy function to create a UEL listing as mentioned previously in the section about rgdx :. The above code will create foo.
If a user would like to create a set with set elements only at specified indices, one could do so by entering the indices in the val field.
Now the above would result in a set with only elements existing in the indices specified in the val field. If a user enters a structure with only two fields, name and uels, as in the example given in the introduction of this section structure s , then wgdx will create a full set corresponding to the global uels. We will give a simple example of a nonlinear optimization problem that would benefit from this capability and describe the steps that are needed in order to use our interface in this application. For example, the clipboard can be used to transfer meta files in the PC enviroment, or encapsulated postscript files can be generated.
The following code is an example of rescaling printed out.
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Note that the output of this routine is saved as a jpeg file "rescale. Other examples of uses of the utility outlined in this paper can be found in the "m" files:. The authors would like to thank Alexander Meeraus and Michael R. Bussieck of GAMS corporation for constructive comments on the design and improvement of this tool. Thanks to Rishabh Jain for work on an earlier version. This section describes the installation procedure for all types of machines.
The following section describes the testing procedure for verifying a correct installation. In addition, these tests create a log file that can be useful when things don't work as expected. To run the tests, carry out the following steps. It provides information about symbols in a specified GDX file. When used with an output argument, information about the symbols in the GDX file is returned as an array of structures. This meta-data can be used in a variety of ways and is especially useful when programming. For example, the first three symbols are non-indexed and the last symbol is indexed in the output from this call:.
It accepts no output arguments. It is especially useful to see the entire contents of smaller GDX files. Further information about what is displayed can be found in the GAMS documentation of the gdxdump utility. This routine can take multiple input arguments and can return multiple output arguments. Its standard syntax is as follows:. Here note that the first argument of gams is the GAMS model name plus any user specific command line settings.
If a user wants to solve the given model in this case found in qp. This feature allows a user to change the execution time behavior of the model. The rest of the input arguments of GAMS are structures. Their positioning is not important. These structures are of two kinds; one is similar to the input structure of wgdx and the other structure has just two string fields, name and val.
We will explain it in detail a later section. The first step is to generate a working GAMS model. The optimal value is 0. Here it should be noted that any model that you want to execute using the MATLAB gams routine should contain something like. As these files can be very large, it is wise to have this statement near the start of the file.
The last line of the model should always be.
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The purpose of setting the first and last line of the model in this manner is to specify what data the user wants to export to MATLAB in a "header" of the model. In the previous example, there is only one output argument, thus the gams routine will get data for its first element from the output gdx file and store it in the MATLAB output argument.
As mentioned earlier, the gams routine takes input arguments in structured form. It allows two different types of structure input.
One contains the symbol data similar to the wgdx input structure, to be exported to the GDX file. The other structure will just have two string fields 'name' and 'value'. Example use:. The second change is an optional additional input field in addition to those given in Section Input Structure called "load". Until now we have seen how to specify different input to the gams routine and in this section we will see how to change the default behavior of a gams call.
There are currently nine fields that can be set in that structure that affect the behavior of the program. Except the uels field, all other string fields take case insensitive data. These are as follows:. The output of gams is similar to rgdx but unlike the rgdx gams routine it doesn't take input specific to a particular symbol. Thus it becomes important to implement a way to change the default behavior of the output.
All these fields behave similar to that described in rgdx and take the same input as of rgdx. Author Steven Dirkse sdirkse gams. Michael C. Ferris ferris cs.
Basic syntax The basic syntax for irgdx is irgdx 'gdxFileName', 'sym1', 'sym2', Renaming The details of this section are rather involved; it can be skipped without loss of continuity. Basic syntax The basic syntax for iwgdx is: iwgdx 'fileName','sym1','sym2', Pass by reference syntax When using the basic iwgdx syntax, a copy of the workspace variable to be written to GDX is made as part of the call. Dimensionality specification It is possible to specify the number of dimensions i. The 1-dimensional symbol p1. The scalar variable p1 was promoted to a 1-dimensional symbol by adding an additional singleton dimension.
The 1-dimensional symbol d1. The 2-dimensional symbol p2. The vector variable p2 was promoted to a 2-dimensional symbol by adding an additional singleton dimension. The 2-dimensional symbol d2.
The 3-dimensional symbol p3. The matrix variable d2 was promoted to a 3-dimensional symbol by adding an additional singleton dimension. Independently, call-by-reference was used to rename d2 to p3. Indexing with labels UELs To this point we have been looking at functions to read irgdx , Section irgdx and write iwgdx , Section iwgdx indexed parameters from and to GDX. Input structure To read a symbol from a GDX file we just need to know its name in string format.