Altering equation

Problems with modeling
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mapo17af

Altering equation

Post by mapo17af » 3 months ago

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:

Code: Select all

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

Code: Select all

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

Code: Select all

 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!
Attachments
Wanted equation.PNG
Preferred equation
Wanted equation.PNG (3.77 KiB) Viewed 109 times
OldEquations.PNG
Current Equations
OldEquations.PNG (5.71 KiB) Viewed 109 times

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