nonlinear regression with constraints

[Ibrahim Bostan]

Hello,
I am able to estimate the parameters (b1,b2) of the model below. My question is how can i put a constraint so that sum of ( exp({-b1}*lag))*(1-exp(-{b2}*lag))) over lag (1,2,3,4, ....35) is unity.

nl ( dep_var= cited_65_69* i_class_1* i_gyearctng_1*( exp({-b1}*lag))*(1-exp(-{b2}*lag)))

thanks a lot in advance
Ibrahim

[Nick Cox]

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[Dirk Enzmann]

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