search for: nonposit

...w to work with R is to estimate a translog production function by sfa or other related function in frontier package, and then use the Ray 1998 formula to find the scale efficiency. However, as the textbook Coelli et al 2005 point out that the concavity may not be satisfied, one needs to impose the nonpositive definiteness condition so that the scale efficiency <1. How can I do it with frontier package? Is there any other SFA model/function in R recommended to find out the scale efficiency and optimal scale? Thanks, Miao [[alternative HTML version deleted]]

Dear R users, while I enjoy the built-in log argument to the plot() function, I wished it would be as easy to create more general custom transformed axes such as sqrt(), logit, etc... for example, instead of plot(x=exp(rnorm(10)), y=(1:10)^4, log = "xy"), sth. along the lines of plot(x=exp(rnorm(10)), y=(1:10)^4, trans = list(x = log, y = sqrt)) to encode the desired transfomation.

Dear R Users, I am trying to obtain a best-fit analytic distribution for a dataset with 11535459 entries. The data range in value from 1 to 300000000. I use: fitdistr(data, "gamma") to obtain mle's for the parameters. I get the following error: Error in optim(start, mylogfn, x = x, hessian = TRUE, ...) : non-finite finite-difference value [1] And the following warnings:

Hi, R guys: I'm using L-BFGS-B method of optim for minimization problem. My function called besselI function which need non-negative parameter and the besselI will overflow if the parameter is too large. So I set the constraint box which is reasonable for my problem. But the point outside the box was test, and I got error. My program and the error follows. This program depends on CircStats

...all, derived-to-virtual-base conversion, dynamic_cast, or typeid, or using the value of a reference bound to such a glvalue. > - Base-to-derived cast on wrong polymorphic type > - Binding a reference to an inappropriately-aligned address or to an empty lvalue > - VLA size evaluates to a nonpositive value > - Reaching the end of a function with a non-void return type, in C++ (in C, this is only UB if the caller uses the return value) > - Overflow in conversion from floating point to smaller floating point or to integral type > - Overflow in conversion from integral type to float...

Hi R users, I am trying to use the optim function to maximize a likelihood funciton, and I got the following warning messages. Could anyone explain to me what messege 31 means exactly? Is it a cause for concern? Since the value of convergence turns out to be zero, it means that the converging is successful, right? So can I assume that the parameter estimates generated thereafter are reliable MLE

1. Martin Maechler's comments should be taken as replacements for anything I wrote where appropriate. Any apparent conflict is a result of his superior knowledge. 2. 'eigen' returns the eigenvalue decomposition assuming the matrix is symmetric, ignoring anything in m[upper.tri(m)]. 3. The basic idea behind both posdefify and nearPD is to compute the