MEX files from MATLAB version 5 are no longer supported in MATLAB 7.4 (R2007a). Also, please note that the file extension of 32-bit Windows MEX-files was changed from ".dll" to ".mexw32" in MATLAB 7.1 (R14SP3).
To work around the issue, you can re-compile the original MEX-file using the MEX command. You may find more details about the MEX command by executing the following at the MATLAB command prompt:
In MATLAB R11 and earlier, MEX-files on Windows were linked directly with the MATLAB executable. With R12, core functionality was broken out into separate DLLs (e.g., libmx.dll, libmat.dll). To preserve binary compatibility with MEX-files from previous releases, a proxy-based compatibility layer was introduced into MATLAB.EXE. This enabled loading of older MEX-files by forwarding API functions to their new locations in the sub-component DLLs. We no longer support V5 MEX-files and, therefore, no longer support this transition mechanism.
As such, MEX files created in R11 or possibly earlier will work in releases up to R2006b, but will fail with later releases. MEX files created in R12 or later releases should work in releases up to at least R2011b, and possibly later releases.
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