optimizing fails on simple example when draws > 0

[ksvanhorn]

Summary:

Running the simple example given in the documentation for rstan::optimizing, but adding a nonzero value for draws, results in an error.

Description:

The documentation for rstan::optimizing gives the following example code:

m <- stan_model(model_code = 'parameters {real y;} model {y ~ normal(0,1);}')
f <- optimizing(m, hessian = TRUE)

This runs fine, but if I add a nonzero draws parameter

m <- stan_model(model_code = 'parameters {real y;} model {y ~ normal(0,1);}')
f <- optimizing(m, hessian = TRUE, draws=10)

it fails with this error:

Error in dimnames(x) <- dn : 
  length of 'dimnames' [2] not equal to array extent

Reproducible Steps:

See above.

Current Output:

See above.

Expected Output:

Successful completion of call.

RStan Version:

2.18.1

R Version:

R version 3.4.3 (2017-11-30)

Operating System:

macOS High Sierra (version 10.13.6)

[ksvanhorn]

Same error if I do

m <- rstan::stan_model(model_code = 'data { int N; vector[N] y; } parameters {real mu;} model {y ~ normal(mu,1); }')
f <- rstan::optimizing(m, hessian = TRUE, draws=10, data=list(N=100, y=rnorm(100, 0.5, 1)))

But if I have two parameters the problem goes away:

m <- rstan::stan_model(model_code = 'data { int N; vector[N] y; } parameters {real mu; real<lower=0> sigma; } model {y ~ normal(mu,sigma); }')

[bob-carpenter]

I'd like to see regression tests added whenever this kind of stuff gets fixed. But I'd really like to see all the basic services tested for their various combinations of inputs and outputs to make sure they work. A good start would just to be to make sure that the basics work for each of the sampling, optimizing, and vb operations.