DIFFXQ Version 1.6

Author: William M. Chan

Description:

This program is used to identify differences between two grid or solution files with identical number of grids and grid dimensions.

Input

The code will interactively prompt for all necessary input, including input grid or solution files, and output filename. The following command-line arguments will override the prompt (if the use specifies a filename as a command-line argument, the code will not prompt for it):

Argument Description

-i File1 File2 Names of two input files

-o OFile output filename

-v for more verbose output

Argument	Description
-i File1 File2	Names of two input files
-o OFile	output filename
-v	for more verbose output

Input file formats

The input grid files must be in 3D PLOT3D format, and input solution files must be in 3D PLOT3D or Overflow format.

Output

For grid files, the output file is a PLOT3D fake Q file where

Q1 = difference in iblanks
Q2 = difference in x
Q3 = difference in y
Q4 = difference in z
Q5 = distance between corresponding grid points

For solution files, the output file is the same file type as the input solution files (PLOT3D or OVERFLOW). Each Q variable in the output file corresponds to differences in that Q variable in the input files.

Future Work:

Implementation of differences in various scalar functions of flow variables, e.g., pressure, density, temperature, etc.

Last modified: Thu Feb 5 12:16:39 PST 2026