NJOY Input

Beginning with NJOY97, the standard Fortran "read *" method is used to read input quantities and strings. Earlier versions used a home-grown scheme with similar properties. The main difference between these two approaches is that the new one delimits string data with single quote characters, but the old one used star characters.

All input is free form, and different quantities can be separated with spaces or commas. Numerical quantities can be given with or without decimals, and "E" or "e" can be used for scientific notation. String input consisting of single words that start with an alphabetic character do not require delimiters. Longer strings with spaces and special characters must be surrounded by single quote characters.

Lines of input for NJOY are often organized so that the parameters at the ends of the lines have default values. Therefore, you can often stop giving numbers before the entire I/O list is exhausted by using the slash (/), or division sign, character. Some examples follow:

      1    reconr
      2    20 21
      3    1395 1/
      4    .01/
      5    '92-U-235'/

Line 1 is a string value that doesn't require delimiters. Line 2 is a line with only two values in the I/O list, and both are given. No terminating / is required. Line 3 is a line with three items in the I/O list. The last variable, namely ngrid, will take its default value of 0. Line 4 has 4 values, and the last three will all be defaulted. The value .01 could also be written as 1e-2 or 1.0e-2. Line 5 has only one value, which is a string. Since the string has spaces and starts with a digit, it has to be delimited with quote characters. Any line that consists of string data must end with the / character.

The NJOY97 test problems provide numerous examples of the input syntax.


23 January 2013 T-2 Nuclear Information Service ryxm@lanl.gov