Hi!
I'm faced the next problem:
suppose I have a vector of some coefficient and for some purpose from
these coefficients I need dynamically build a functional expression
(because, the number of elements in the vector of coefficients might
differ each time). So, I'm trying to do like this (let the number of
coefficients be 3):
Building expression
foo <- gsub(",","*",toString(paste('(p',1:3,'*x +
(1-p',1:3,'))',sep="")))
foo
[1] "(p1*x + (1-p1))* (p2*x + (1-p2))* (p3*x + (1-p3))"
But now, how can I take derivative of this expression w.r.t. "x"?
dfoo <- D(foo,"x") #doesn't work as well as
dfoo <- D(as.expression(foo),"x")
May be there are other ways to handle this kind of situation?
Best regards,
Oleksandr
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