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Altering equation

Posted: Thu Apr 04, 2019 9:25 pm
by mapo17af
I want to alter an existing model in GAMS, by changing an equation.
Please see the screenshot attached for the equation that I want to code and for the existing one that I would like to alter.

I tried the following:

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ga(t)=((1-psi)*(ga0)+ psi*ga(t-1))*(exp(-dela*5*((t.val-1)))));
        al("1") = a0; loop(t, al(t+1)=al(t)/((1-ga(t))););
Hereby, the part

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(exp(-dela*5*((t.val-1))))
and

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 al("1") = a0; loop(t, al(t+1)=al(t)/((1-ga(t))););
were already in the original code.

My questions are:
- would the above coding give me the preferred equation ? (if I define the parameters earlier onward in the code)
- How should I include epsilon in the formula that I want to code?
Epsilon is an i.i.d. residual from an AR(1) (auto-regressive process of order 1) based on almost 200 years of empirical data. i.e. it is not a parameter that I define myself.

If it is of any relevance: these equations relate to the DICE model of William Nordhaus

Many thanks!