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

Ask for a display of a variable or equation and you receive

—-## VAR MAKECHAIR

## MAKECHAIR(PLANT2,FUNCTIONAL,NORMAL)

OBJT | 15.000 |

RESOURCEQ(PLANT2,SMLLATHE) | 0.80000 |

RESOURCEQ(PLANT2,LRGLATHE) | 0.50000 |

TRNCHAIREQ(PLANT2,FUNCTIONAL) | -1.0000 |

UPPER BOUND | 5000.0 |

or | |

—-## EQU LINKTABLE | |

## LINKTABLE(FANCY) | |

MAKETABLE(PLANT1,FANCY) | -1.0000 |

TRANSPORT(PLANT3,TABLES,FANCY) | -1.0000 |

SELL(PLANT1,DINSETS,FANCY) | 1.0000 |

=L= | 0.00000E+00 |

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Ask about the characteristics of selected variables and equations and you get

Is | Tot | Pos | Neg | Nln | Minimum | Maximum | |

—-### Requested Variables | Non | Cof | Cof | Cof | Cof | Absolute | Absolute |

SELL(PLANT1,TABLES, | 0 | 2 | 1 | 1 | 0 | 1.000 | 1.000 |

FUNCTIONAL) | |||||||

Is | Tot | Pos | Neg | Nln | Minimum | Maximum | |

—-### Requested Equations | Non | Cof | Cof | Cof | Cof | Absolute | Absolute |

RESOURCEQ(PLANT1,LABOR) | 0 | 3 | 3 | 0 | 0 | 1.000 | 5.000 |

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Request a report of the characteristics of equation and variable blocks and you get

Variable | Sign | Numb | Numb | Pos | Neg | Non | Maximum | Minimum |

Block | Res | Vars | Nonl | Coef | Coef | Coef | Absolute | Absolute |

MAKECHAIR | >=0 | 12 | 0 | 60 | 12 | 0 | 1.700 | .2000 |

MAKETABLE | >=0 | 6 | 0 | 16 | 4 | 0 | 5.000 | 1.000 |

Equation | Type | Numb | Numb | Pos | Neg | Non | Pos | Neg | Maximum | Minimum |

Block | Res | Eqns | Nonl | Coef | Coef | Coef | RHS | RHS | Absolute | Absolute |

OBJT | =E= | 1 | 0 | 23 | 10 | 0 | 0 | 0 | 1100. | 5.000 |

RESOURCEQ | =L= | 12 | 0 | 60 | 0 | 0 | 11 | 0 | 5.000 | .2000 |

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Examine a GAMS model to see whether any variables and equations contain specification errors and you get messages like the following

—-### Analysis of Variables ( nonlinear terms at current point)

**** Warning These variables will equal zero because they have a zero lower bound an undesirable object function coefficient all 0 or – coefficients in the =G= rows all 0 or + coefficients in the =L= rows and no coefficients in the =E= rows

## MAKETABLE(PLANT2,FUNCTIONAL)

MAKETABLE(PLANT2,FANCY)

—-### Analysis of Equations ( nonlinear terms at current point)

**** Warning This =L= constraint causes all variables in it to have a zero solution value since the nonnegative variables present have only 0 or + coefficients the nonpositive variables present have only 0 or – coefficients the unrestricted variables have only zero coefficients and the rhs is zero.

## RESOURCEQ(PLANT2,TOP)

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You can generate a schematic of the structure of the variable and equation blocks and you get something like

| | M | M | T | N | | | |||||

| | A | A | R | E | | | |||||

| | K | K | A | T | | | |||||

| | E | E | N | I | | | |||||

| | C | T | S | N | | | |||||

| | H | A | P | S | C | | | ||||

| | A | B | O | E | O | | | R | |||

| | I | L | R | L | M | | | H | |||

| | R | E | T | L | E | | | S | |||

OBJT | | | + | + | + | – | + | | | E | 0 | |

RESOURCEQ | | | + | + | | | L | + | ||||

LINKTABLE | | | – | – | + | | | L | 0 | |||

LINKCHAIR | | | – | + | | | L | 0 | ||||

TRNCHAIREQ | | | – | + | + | | | L | 0 | |||

TRNTABLEEQ | | | – | + | + | | | L | 0 | |||

Variable Typ | | | + | + | + | + | u |

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Ask for a block picture and you can examine the number of coefficients in the intersections of variable and equation blocks

| | | | C | # | ||||||||

| | M | M | T | N | | | o | |||||

| | A | A | R | E | | | e | o | ||||

| | K | K | A | T | | | f | f | ||||

| | E | E | N | I | | | f | |||||

| | C | T | S | N | | | ||||||

| | H | A | P | S | C | | | C | E | |||

| | A | B | O | E | O | | | R | n | q | ||

| | I | L | R | L | M | | | H | t | n | ||

| | R | E | T | L | E | | | S | s | s | ||

| | — | — | — | — | — | | | — | — | — | — | |

OBJT | | | 12+ | 4+ | 6+ | 1+ | | | E | 0 | 23+ | 1 | |

| | 10- | | | 10- | ||||||||

RESOURCEQ | | | 48+ | 12+ | | | L | 11+ | 60+ | 12 | |||

| | | | ||||||||||

LINKTABLE | | | 4+ | | | L | 0 | 4+ | 2 | ||||

| | 2- | 2- | | | 4- | |||||||

LINKCHAIR | | | 2+ | | | L | 0 | 2+ | 2 | ||||

| | 4- | | | 4- | ||||||||

TRNCHAIREQ | | | 4+ | 4+ | | | L | 0 | 8+ | 4 | |||

| | 12- | | | 12- | ||||||||

TRNTABLEEQ | | | 2+ | 2+ | | | L | 0 | 4+ | 2 | |||

| | 2- | | | 2- | ||||||||

| | — | — | — | — | — | | | — | — | — | — | |

Coeff Cnts | | | 60+ | 16+ | 12+ | 12+ | 1+ | | | 11+ | 101+ | ||

| | 12- | 4- | 6- | 10- | | | 32- | |||||

# of Vars | | | 12 | 6 | 6 | 10 | 1 | | | ||||

Variable Typ | | | >=0 | >=0 | >=0 | >=0 | <0> |

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Ask for a block picture and you can look at the scaling characteristics of the variable and equation blocks

| | | | R | E | |||||||

| | M | M | T | N | | | H | q | |||

| | A | A | R | E | | | S | u | |||

| | K | K | A | T | | | |||||

| | E | E | N | I | | | M | M | |||

| | C | T | S | N | | | a | a | |||

| | H | A | P | S | C | | | x | x | ||

| | A | B | O | E | O | | | M | M | ||

| | I | L | R | L | M | | | i | i | ||

| | R | E | T | L | E | | | n | n | ||

| | — | — | — | — | — | | | — | — | ||

OBJT | Max | | | 26.6 | 100 | 20 | 1100 | 1 | | | 0 | 1100 |

Min | | | 15 | 80 | 5 | 82 | 1 | | | 0 | 1 | |

RESOURCEQ | Max | | | 1.7 | 5 | 0 | 0 | 0 | | | 210 | 5 |

Min | | | 0.2 | 1 | 0 | 0 | 0 | | | 40 | 0.2 | |

LINKTABLE | Max | | | 0 | 1 | 1 | 1 | 0 | | | 0 | 1 |

Min | | | 0 | 1 | 1 | 1 | 0 | | | 0 | 1 | |

LINKCHAIR | Max | | | 0 | 0 | 1 | 6 | 0 | | | 0 | 6 |

Min | | | 0 | 0 | 1 | 4 | 0 | | | 0 | 1 | |

TRNCHAIREQ | Max | | | 1 | 0 | 1 | 1 | 0 | | | 0 | 1 |

Min | | | 1 | 0 | 1 | 1 | 0 | | | 0 | 1 | |

TRNTABLEEQ | Max | | | 0 | 1 | 1 | 1 | 0 | | | 0 | 1 |

Min | | | 0 | 1 | 1 | 1 | 0 | | | 0 | 1 | |

| | — | — | — | — | — | | | — | — | ||

Total Var | Max | | | 26.6 | 100 | 20 | 1100 | 1 | | | 210 | |

Min | | | 0.2 | 1 | 1 | 1 | 1 | | | 40 |

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You can generate a schematic for small GAMS models or portions of larger models depicting the location of coefficients by sign and magnitude as follows

| | R | |||||||||||||

| | T | T | T | T | T | T | H | |||||||

| | R | R | R | R | R | R | S | P | N | |||||

| | A | A | A | A | A | A | O | E | R | |||||

| | N | N | N | N | N | N | C | S | G | O | ||||

| | S | S | S | S | S | S | O | I | A | A | A | W | ||

| | P | P | P | P | P | P | E | T | I | T | I | C | ||

| | O | O | O | O | O | O | F | I | J | I | J | N | ||

| | R | R | R | R | R | R | F | V | V | T | ||||

| | T | T | T | T | T | T | S | E | S | E | S | S | ||

| | ||||||||||||||

| | 1 | 2 | 3 | 4 | 5 | 6 | ||||||||

———— | ||||||||||||||

OBJT 1 | | | D | E | E | D | D | 6 | = 0 | 11 | 1 | 12 | |||

LINKTABLE 1 | | | 3 | <0 | 0 | 1 | 1 | ||||||||

LINKTABLE 2 | | | 3 | <0 | 0 | 1 | 1 | ||||||||

LINKCHAIR 1 | | | 3 | 3 | <0 | 0 | 2 | 2 | |||||||

LINKCHAIR 2 | | | 3 | 3 | <0 | 0 | 2 | 2 | |||||||

TRNCHAIREQ 1 | | | C | <0 | 1 | 1 | |||||||||

———— | ||||||||||||||

LOWER BND | | | 0 | 0 | 0 | 0 | 0 | 0 | |||||||

UPPER BND | | | + | + | + | + | + | + | |||||||

———— | ||||||||||||||

POSITIVE | | | 3 | 0 | 3 | 0 | 3 | 0 | |||||||

COLUMN CTS | | | 0 | 3 | 0 | 3 | 0 | 2 | |||||||

NEGATIVE | | | 1 | 0 | 1 | 0 | 1 | 0 | |||||||

COLUMN CTS | | | 0 | 1 | 0 | 1 | 0 | 2 |

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Ask to reconstruct the reduced costs after a model solution and you get

—-### BUDGETING VARIABLES | |||

—-## VAR MAKECHAIR | |||

## MAKECHAIR(PLANT2,FANCY,NORMAL) | |||

SOLUTION VALUE | 73.0195 | ||

UPPER BOUND | 5000.00 | ||

EQN | Aij | Ui | Aij*Ui |

OBJT | 25.000 | 1.0000 | 25.000 |

RESOURCEQ(PLANT2,SMLLATHE) | 1.2000 | 47.770 | 57.324 |

RESOURCEQ(PLANT2,LRGLATHE) | .70000 | 38.830 | 27.181 |

RESOURCEQ(PLANT2,LABOR) | .80000 | 19.369 | 15.495 |

TRNCHAIREQ(PLANT2,FANCY) | -1.0000 | 125.00 | -125.00 |

TRUE REDUCED COST | .00000E+00 |

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Ask to reconstruct the activity within equations after a model solution and you get

—-### ROW SUMMING EQUATIONS | |||

—-## EQU RESOURCEQ | |||

## RESOURCEQ(PLANT2,SMLLATHE) | |||

VAR | Aij | Xj | Aij*Xj |

MAKECHAIR(PLANT2,FUNCTIONAL, | .80000 | 62.233 | 49.787 |

NORMAL) | |||

MAKECHAIR(PLANT2,FANCY,NORMAL) | 1.2000 | 73.020 | 87.623 |

MAKECHAIR(PLANT2,FANCY,MAXLRG) | .50000 | 5.1798 | 2.5899 |

=L= | =L= | ||

RHS COEFF | 140.00 | ||

SLACK EQUALS | .00000E+00 | ||

SHADOW PRICE | 47.770 |

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Ask the program to find variables or equations which could be causing unbounded or infeasible models and you get

—-### THESE VARIABLES ARE POTENTIALLY UNBOUNDED

To find the cause of unboundedness bound them or the objective function variable at a large value. Then solve and manually or through GAMSCHK find large levels for variables in solution

SELL(PLANT1,TABLES,FUNCTIONAL)

—-### THESE EQUATIONS ARE POTENTIALLY INFEASIBLE

RESOUREQ(PLANT1,LABOR)

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