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Better NX Nastran performance with this simple trick

Community Manager Community Manager
Community Manager

Want NX Nastran to perform better, but you’re not sure how to achieve this? A simple trick is to change what 64 bit executable you’re using. Did you know NX Nastran actually comes with two? These are LP-64 and the ILP-64, and they determine how much memory can be allocated.


LP and ILP: What’s the difference?


No matter what release of NX Nastran you run, each comes with the two versions of executables mentioned above. LP-64 uses 32 bit integers and is limited to 8 GB of RAM regardless of how many gigs of memory your machine has installed. ILP-64 on the other hand uses 64 bit integers and can address over 20 million TB—yes, that’s terabytes!  So you’re limited only by the amount of memory installed on your machine.


When should I use ILP over LP?


If your NX Nastran model requires more than 8 GB of RAM (and you have more memory installed on your machine), you will want to use ILP-64. Less than 8GB of RAM to solve, and you may want to try LP-64. It will generate slightly smaller scratch files, which may reduce solution time.


So how do I tell what version I’m running?


To determine which version of NX Nastran you’re running, check the name of the executable. nastran64.exe or nastran64w.exe both refer to LP-64, while nastran64L.exe and nastran64Lw.exe refer to ILP-64. In other words, look for the "L" in the name if you want to use ILP. 


Nastran Versions.jpg


Executables with a “w” are intended to be used by desktop shortcuts, start menu and taskbar icons. The “w” indicates a small dialog window will pop-up with a file browser to allow you to select an input deck. 


If you want to run executables from a command line or in a batch script, you’ll want to use those that do not have “w” in the file name.


If you already ran the simulation and aren’t sure which executable you used, you can look at the .f06 or .log file to determine this.