R help - Apr 2019 - Advice for speeding up optim()

Hi all,

I?m calling optim() and getting correct results, but need help to upscale it. I
need to call it on a matrix that?s 3000x5000. I know the SANN option is slow but
I get similar results with all other options. Perhaps there?s another package..I
also heard about implementing my loss function in the cpp core but I?m not sure
what this entails. I do have bounds for both parameters. My function is below ?
thank you in advance for your patience and suggestions!

rvog = function(x){
                ext = x[1]
                height = x[2]
                ext_linear = ext * log(10)/20 #change units to nepers per meter
                inc_radians = myinc *pi/180
                p1 = 2*ext/cos(inc_radians)
              p2 = p1 + 1i*mykz
                #minimize distance to a provided coherence value
              coh = abs(mycoh - ((p1 / p2) * ((exp(p2*height)-1) /
(exp(p1*height)-1))))
                return (coh)
}

#ancillary variables
mykz = kz[i,j]
myinc = inc
mycoh = volume

#call optimization function
myoptim = optim(c(0.05,30), rvog, method = "SANN", control =
list(maxit = 30000, temp = 2000, trace = FALSE))

~Naiara.

	[[alternative HTML version deleted]]

Really should always look at Task Views

There's optimx package.

JN

On 2019-04-02 10:13 p.m., Pinto, Naiara (334F) via R-help
wrote:
> Hi all,
> 
> I?m calling optim() and getting correct results, but need help to upscale
it. I need to call it on a matrix that?s 3000x5000. I know the SANN option is
slow but I get similar results with all other options. Perhaps there?s another
package..I also heard about implementing my loss function in the cpp core but
I?m not sure what this entails. I do have bounds for both parameters. My
function is below ? thank you in advance for your patience and suggestions!
> 
> rvog = function(x){
>                 ext = x[1]
>                 height = x[2]
>                 ext_linear = ext * log(10)/20 #change units to nepers per
meter
>                 inc_radians = myinc *pi/180
>                 p1 = 2*ext/cos(inc_radians)
>               p2 = p1 + 1i*mykz
>                 #minimize distance to a provided coherence value
>               coh = abs(mycoh - ((p1 / p2) * ((exp(p2*height)-1) /
(exp(p1*height)-1))))
>                 return (coh)
> }
> 
> #ancillary variables
> mykz = kz[i,j]
> myinc = inc
> mycoh = volume
> 
> #call optimization function
> myoptim = optim(c(0.05,30), rvog, method = "SANN", control =
list(maxit = 30000, temp = 2000, trace = FALSE))
> 
> ~Naiara.
> 
> 	[[alternative HTML version deleted]]
> 
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