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Equations have attributes that can be used in specifying starting values, and scaling. The attributes also contain the solution level and marginal for the equation after execution of a solve statement. They are extensively discussed in the Calculations chapter and represent:
Equation attribute
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Symbol
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Description
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Lower bound
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.lo
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Negative infinity or the right hand side of a =g= or =e= equation.
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Upper bound
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.up
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Positive infinity or the right hand side of a =l= or =e= equation.
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Equation level
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.l
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Optimal level for the equation which is equal to the level of all terms involving variables.
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Marginal
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.m
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Dual, shadow price or marginal value for the equation. This attribute is reset to a new value when a model containing the equation is solved.
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Scale factor
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.scale
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Numerical scaling factor that scales all coefficients in the equation providing the model attribute scaleopt is set to 1. This is discussed in the Scaling GAMS models chapter.
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The user distinguishes between these attributes by appending a suffix to the equation name.
Examples:
(model.gms)
SUPPLYEQ.scale(SUPPLYL)=33;
marg(supplyl)=SUPPLYEQ.m(SUPPLYL);
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