The table below lists the most common errors in GAMS. In order to learn how to find an error and correct it, go to lesson 8.
| N° | Error message | Description | Example (from the Wheat/Maize farm model) |
| 8 | Error 8 ‘)’ expected |
OBJECTIVE.. sum(c, mb(c)*X(c) =e= Z ;
* ) forgotten in order to close the sum |
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| 36 | Error 36 ‘=’ or ‘..’ or ‘:=’ or ‘$=’ operator expected rest of statement ignored |
Among other possibilities, the two dots were forgotten after the name of the equation in the attribution.
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OBJECTIVE sum(c, mb(c)*X(c) = Z ; * (..) omitted after OBJECTIVE |
| 37 | Error 37 ‘=l=’ or ‘=e=’ or ‘=g=’ operator expected |
In GAMS equations, signs are indicated as follows : « equal » is written « =e= », « less than or equal to » is written « =l= » (means lower than) and « greater than or equal to » is written « =g= » (means greater than) | OBJECTIVE.. sum(c, mb(c)*X(c) = Z ;
*instead of =e= we wrote = |
| 71 | Error 71 The symbol shown has been declared as an equation, but no Symbolic equation (..) was found. hint – look for commas in the Documentation text for the equations. use quotes around the Text or eliminate the commas. |
An equation has been declared but has not been attributed.
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| 96 | Error 96 Blank needed between identifier and text (-or- illegal character in identifier) (-or- check for missing ‘;’ on previous line |
Common error implying that a semi-colon has been omitted. | OBJECTIVE EQUATIONS
objective function |
| 120 | Error 120 Unknown identifier entered as set |
When it should have a SET, GAMS reads another identifier
|
PARAMETER BMO(V) labour needs per hectare and per crop (hours) /wheat 25 maize 50/ ;*V instead of C in BMO(V) |
| 140 | Error 140 Unknown symbol |
GAMS does not recognize the symbol used. This may be because you forgot to declare an entity. | |
| 160 | Error 160 Unique element expected – a starting symbol was encountered and parsing will continue by entering ‘element’. An UNQUOTED element has to start with a letter or digit followed by letters, digits, ‘+’, ‘-‘ or ‘_’. The length is limited to 63 characters. The following words are reserved (starting symbols of a GAMS statement) and cannot be used for UNQUOTED set elements:ABORT, ACRONYM(S), ALIAS, BINARY, DISPLAY, ELSE EQUATION(S), EXECUTE, FILE(S), FOR, FREE, IF, INTEGER, LOOP MODEL(S), NEGATIVE, OPTION(S), PARAMETER(S) POSITIVE, PROCEDURE(S), PUT, PUTCLEAR, PUTCLOSE, PUTHD PUTPAGE, PUTTL, SCALAR(S), SEMICONT, SET(S), SOS1, SOS2 TABLE, VARIABLE(S), WHILE QUOTED elements can contain any character. Single and double quotes can be used (starting and ending quote have to match) |
One of the elements that you declared does not meet GAMS norms : start with a letter or a number, followed by letters, numbers, ‘+’, ‘-‘ or ‘_’ and a maximum of 63 characters. Furthermore, you may not use a reserved word. | SET C crop / table, but/ ;
* the word table was used, which is a WORD RESERVED for the element, instead of wheat |
| 170 | Error 170 Domain violation for element |
The element does not belong to the domain (in most cases to SET) defined | sets C crops /wheat,maize/ ; parameter BMO(C) /barley 25 maize 50/ ;*barley is not an element of C |
| 338 | Error 338 Unique element expected – symbol was not an element and the following text will be skipped until a proper symbol is found to recover. Remember that an UNQUOTED element has to start with a letter or digit followed by letters, digits, ‘+’, ‘-‘ or ‘_’. The length is limited to 63 characters. The following words are reserved (starting symbols of a GAMS statement) and cannot be used for UNQUOTED set elements: ABORT, ACRONYM(S), ALIAS, BINARY, DISPLAY, ELSE EQUATION(S), EXECUTE, FILE(S), FOR, FREE, IF, INTEGER, LOOP MODEL(S), NEGATIVE, OPTION(S), PARAMETER(S) POSITIVE, PROCEDURE(S), PUT, PUTCLEAR, PUTCLOSE, PUTHD PUTPAGE, PUTTL, SCALAR(S), SEMICONT, SET(S), SOS1, SOS2 TABLE, VARIABLE(S), WHILE QUOTED elements can contain any character. Single and double quotes can be used (starting and ending quote have to match) |
One of the elements declared does not meet GAMS norms : start with a letter or a number, followed by letters or numbers, ‘+’, ‘-‘ or ‘_’ and a maximum of 63 characters. Furthermore, you may not use a reserved word. | SET C crops / +wheat, +maize/ ;
* the name +wheat and +maize was given to the elements instead of wheat and maize |
| 409 | Error 409
Unrecognizable item – skip to find a new statement looking for a ‘;’ or a key word to get started again |
EQUATIONS OBJECTIVE objective function LAND soil constraint LABOUR labour constraint ; OBJECTIVE.. sum(c, mb(c)*X(c)) =e= Z ; LABOUR.. sum(c, bmo(c)*X(c)) =l= dmo ; LAND.. sum(c, X(c)) =l= dterre *omission ; here |
Errors at the end of the model which indicate that resolution has not been successfully carried out :
Error 256
Error(s) in analysing solve statement. More detail appears
Below the solve statement above
Error 257
Solve statement not checked because of previous errors