apollo_makeGrad {apollo}  R Documentation 
Creates gradient function.
Description
Creates gradient function from the likelihood function apollo_probabilities provided by the user. Returns NULL if the creation of gradient function fails.
Usage
apollo_makeGrad(
apollo_beta,
apollo_fixed,
apollo_logLike,
validateGrad = FALSE
)
Arguments
apollo_beta 
Named numeric vector. Names and values for parameters. 
apollo_fixed 
Character vector. Names (as defined in 
apollo_logLike 
Function to calculate the loglikelihood of the model, as created by apollo_makeLogLike If provided, the value of the analytical gradient will be compared to the value of the numerical gradient as calculated using apollo_logLike and the numDeriv package. If the difference between the two is bigger than 1 that the analytical gradient is wrong and NULL will be returned. 
validateGrad 
Logical. If TRUE, it compares the value of the analytical gradient evaluated at apollo_beta against the numeric gradient (using numDeriv) at the same value. If the difference is bigger than 1 return NULL. 
Details
Internal use only. Called by apollo_estimate
before estimation.
The returned function can be singlethreaded or multithreaded based on the model options.
Value
apollo_gradient function. It receives the following arguments

b
Numeric vector of _variable_ parameters (i.e. must not include fixed parameters). 
countIter
Not used. Included only to mirror inputs of apollo_logLike. 
getNIter
Not used. Included only to mirror inputs of apollo_logLike. 
sumLL
Not used. Included only to mirror inputs of apollo_logLike. 
writeIter
Not used. Included only to mirror inputs of apollo_logLike.
If the creation of the gradient function fails, then it returns NULL.