R help - Apr 2010 - lm() with non-linear coefficients constraints? --- nls?

dear R experts---quick question.  I need to estimate a model that looks like

 y = (b*T+d*T^3) + (1-b-3*d*T^2)*x + (3*d*T)*x^2 + (-d)*x^3

I only have three parameters.  Is nls() the right tool for the job, or is
there something faster/better?

/iaw

----
Ivo Welch (ivo.welch@brown.edu, ivo.welch@gmail.com)

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dear R experts---quick question.  I need to estimate a model that looks like

 y = (b*T+d*T^3) + (1-b-3*d*T^2)*x + (3*d*T)*x^2 + (-d)*x^3

I only have three parameters.  Is nls() the right tool for the job, or is
there something faster/better?

/iaw
----
Ivo Welch (ivo.welch@brown.edu, ivo.welch@gmail.com)
CV Starr Professor of Economics (Finance), Brown University
http://welch.econ.brown.edu/

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