s = newext(old, new, fname, delim )
Return a string for a file name with a new extension. The extension delimiter can be specified to allow other changes in file names. The following rules take place:
String with old extension.
String with new extension.
Name of file.
Specifies the extension delimeter to use. Default is '˙'. If delim is s tring with more than one character,all of them are used as the extension delimiter.
The new file name.
Pierre Jaccard, Geophysical Institute, University of Bergen, 1999