# General GAMSCHK Information – Bruce McCarl

**Source**: https://agecoresearch.tamu.edu/mccarl/gams-related-information/general-gamschk-information/
**Parent**: https://agecoresearch.tamu.edu/mccarl/

[What are the basic functions of GAMSCHK?](#basic)\
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[How is GAMSCHK used in a GAMS program?](#use)\
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[How do I obtain GAMSCHK?](#obtain)\
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[How can I get a copy of the latest writeup?](http://agecon2.tamu.edu/people/faculty/mccarl-bruce/gamschk.htm#writeup)\

**What are the basic functions of GAMSCHK?**

[Examples](https://agecoresearch.tamu.edu/mccarl/functions-of-gamschk-and-examples/)

- Display the structure of user selected equations and/or variables
- List the characteristics of selected groups of variables and equations
- List the characteristics of equation and variable blocks
- Examine a GAMS model to see whether any variables and equations contain specification errors
- Generate a schematic of the structure of the variable and equation blocks
- Examine the number of coeficients in the intersections of variable and equation blocks
- Look at the scaling characteristics of the variable and equation blocks
- Form a schematic for model components depicting the location of coefficients by sign and magnitude
- Reconstruct the reduced cost of variables after a model solution
- Reconstruct the activity within equations after a model solution
- Find variables or equations which could be causing unbounded or infeasible models

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**How is GAMSCHK used in a GAMS program?** \
There are two elements to the use of GAMSCHK

- Modification of the GAMS program
  - In the GAMS program you must make GAMSCHK the chosen solver by entering a line like\
    option lp=gamschk;\
    The rest of the program is like any other GAMS model
- Creation of the gck file
  - In addition GAMSCHK requires that the user indicate which procedures are to be employed. This is specified through the use of the \*.GCK file where the \* refers to the filename from the GAMS execution instruction. Thus if you are solving a model called trnsport you use a file called trnsport.gck.

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**How do I obtain GAMSCHK?**

GAMSCHK is a standard part of all GAMS releases.\
If you do not have a copy you need to update your system.\
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**How can I get a copy of the latest writeup?**

GAMSCHK is a standard part of all GAMS releases. The GAMSCHK manual is included in the Solver Manual Book\
Also a current version can be gotten from [GAMSCHK Documentation](http://agecon2.tamu.edu/people/faculty/mccarl-bruce/papers/531.pdf)\
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