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EES 64-Bit Professional License


The Annual, Commercial and Professional licenses of EES are 32-bit Windows executable programs that are designed to operate on 32-bit or 64-bit Windows operating systems, such as Windows 10 and 11.  There is also a true 64-bit Professional EES license (EES64.exe) that will only work on 64-bit operating systems.  The 64-bit Professional license operates in exactly the same manner as the 32-bit Professional licenses except that it calculates faster and it allows a maximum of 24,000 variables, compared to 12,000 variables with the 32-bit Professional license.  Calculation speeds for the 64-bit license can be a factor of 2 to 3 times faster than the 32-bit license for computationally-intensive problems.   The files written by the 64-bit license have a different format than the corresponding files written with the 32-bit license, which necessitates the use of the additional 64 in the file name extensions. This page summarizes the important differences between the 32 and 64-bit licenses.  


The 64-bit license requires a 64-bit Windows operating system, e.g., Windows 7/8 64 bit.  It will not work on a 32-bit operating system.


A 64-bit license (EES.DFT64) file is required to run the 64-bit license.  This file can be purchased from our Order page.  Note that a Professional license with a current subscription to Instant Update and Technical Support (IUTS) service is required in order to obtain a 64-bit license file.


There is only a 64-bit Professional license.  The Annual and  Commercial licenses will not be able to run in 64-bit mode.


The 64-bit license saves EES files with the .EES64 file name extension.  EES64 files are identified by the file name extension and the yellow EES 64 icon.  Double-clicking on an EES64 file will start the 64-bit EES program.  The 32-bit EES licenses cannot read .EES64 files.    


The 32-bit EES licenses do all floating point calculations using extended floating point numbers having 80 bits of numerical precision.  The 64-bit license uses doubles, which are floating point numbers having 64 bits of precision.  As a result, the 32-bit license provides greater precision and allows larger numerical values than the 64-bit license.  The largest number that the 64-bit license can handle is approximately 1.7E308.   The use of 64-bit doubles is the major reason that the 64-bit license calculates faster than the 32-bit licenses.


Library files in the 64-bit license are saved with the .LIB64 file name extension.  Similarly, EES Lookup files, external functions and procedures are identified with a 64 in the file name extension, e.g., LKT64, .FDL64, .DLF64, and .DLP64.  None of these files can be read by the 32-bit licenses because of the different format of the floating point numbers.


The native form for binary Lookup table files in the 64-bit license of EES is .LKT64.


The 64-bit EES license can read any 32-bit or 64-bit .EES, .LIB file or .LKT file.  However, it is necessary to convert the information in the 32-bit file to equivalent 64-bit information and this conversion process can be slow for large files.  After reading a 32-bit file, save it as 64-bit file so that is will be read quickly the next time it is opened.


The 64-bit license can save all EES, Library and Lookup tables files in a format that can be read by the 32-bit Annual, Commercial and Professional licenses.  EES is programmed to save files in the 32-bit format if the file name extension is .EES or .LIB instead of .EES64 or .LIB64.  The Open and Save As dialogs provide a dropdown control to select various file types, including the 32-bit formats.


The 64-bit license can not read external library files (.FDL, .DLP, .DLF, .DLL) that were created for the 32-bit licenses. It is necessary to recompile these external library files with a 64-bit compiler and save them with  .FDL64, .DLP64, .DLF64, and .DLL64 file name extensions.  


Library files (.LIB64, .FDL64, .DLF64, .DLP64 and .DLL64) are automatically loaded when the 64-bit EES program is started if they are placed in the USERLIB64 folder.


The EES_REFPROP interface (EES_REFPROP.DLL) must be upgraded to operate with the 64-bit license.  The upgrade can be ordered from our Order page.