Therefore, variable and row names may not contain embedded blanks.Yes - see this post.
#Lp to mps converter for mac free
Once again, you can switch to using RC name format to avoid this conflict.Īs a final note, LINGO only supports free format MPS files, and does not support fixed format MPS files. When you go to solve the model, you will receive either error message 28 (Invalid use of a row name), or error message 37 (Name already in use). Notice how the variable names now use RC format, guaranteeing that name collisions will not occur.Īnother potential conflict is that MPS and MPI allow variable names to be duplicated as constraint names and vice versa. Here is the model as it appears after importing it into LINGO: However, this time we will use RC naming conventions. To switch to RC format for MPS names, run the Solver|Optionscommand, select the General Solver tab, then click the checkbox titled Use R/C format names for MPS I/O, as illustrated here:Īs an example, we will once again import the same MPS format model as above. In addition, LINGO renames the objective row to be ROBJ. Similarly, each column (variable) is renamed to Cn. RC format involves renaming each row (constraint) in a model to be Rn, where n is the row’s index.
This option involves using RC format for names encountered during MPS I/O. If name collisions are a problem, then LINGO has an option that will ensure that all names remain unique. This message displays the number of variable and row names that were patched to get them to conform to LINGO syntax.
#Lp to mps converter for mac Patch
However, you will be warned whenever LINGO has to patch a name with the following error message: Of course, situations such as this entirely alter the structure of the model, rendering it incorrect. For instance, the variable names X.1 and X%1 would both get mapped into the single LINGO name X_1. However, there is a chance for name collisions where two or more names get mapped into one. LINGO does this by substituting an underscore for any character in a name that is not admissible. To compensate for this fact, LINGO attempts to patch names when reading a file, so that all the incoming names are compatible with its syntax.
When it comes to acceptable constraint and variable names, the MPS, MPI and LP formats are less restrictive than LINGO. Thus, when saving copies of a model on your own machine, you should always use the File|Save command in order to save models in a native LINGO format (LG4 or LNG) in order to preserve your model in its entirety. These file formats are purely scalar in nature-all set-based information is lost upon saving a LINGO model in either MPS or MPI format (LINGO does not currently write LP format files). The MPS, MPI and LP file formats are intended primarily for exporting (importing) models to (from) other applications or platforms. Should you wish to save the file again using either MPS or MPI format rather than LINGO format, you must use the File|Export File|MPS Format…command. Note how the model is automatically converted from MPS, MPI or LP format to native LINGO format. Using the File|Open command to read either of these three versions of the model into LINGO, we are presented with the following window containing an equivalent LINGO model: One thing to notice at this point is that MPS and MPI formats are not very compact methods for storing a model - they are designed for portability, as opposed to efficiency. ! Name Lower Bound Initial Point Upper Bound TypeĪnd, the LP format version of the model is: As an example, consider the following, simple model: When LINGO reads an MPS, MPI or LP file, it converts the formulation to an equivalent LINGO model. LINGO can also write MPS and MPI format files (but not LP files) this is discussed in the File|Export File section below. When importing a non-native file, LINGO reads the file from disk, converts it to an equivalent LINGO model, and places the model into a new model window. LP, then LINGO will invoke, respectively, its MPS, MPI or LP reader to parse the file. If the file to be opened has an extension of.
At present, LINGO only supports linear models when reading LP format files. However, with LP format equations are stored using standard algebraic format, making LP files much easier to read and interpret than MPS files. LP - The LP file format is another industry standard file format, as is MPS, for storing linear and quadratic model.
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