Make corr_matrix_transform work for size 0 inputs

[mcol]

Summary

Fixes #1430.

Tests

Added test mentioned in the issue.

Side Effects

None.

Checklist

• Math issue corr_matrix_transform should work for size zero inputs #1430

• Copyright holder: Marco Colombo

  The copyright holder is typically you or your assignee, such as a university or company. By submitting this pull request, the copyright holder is agreeing to the license the submitted work under the following licenses:
  - Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
  - Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

• the basic tests are passing

  • unit tests pass (to run, use: ./runTests.py test/unit)
  • header checks pass, (make test-headers)
  • docs build, (make doxygen)
  • code passes the built in C++ standards checks (make cpplint)

• the code is written in idiomatic C++ and changes are documented in the doxygen

• the new changes are tested

[stan-buildbot]

(stat_comp_benchmarks/benchmarks/gp_pois_regr/gp_pois_regr.stan, 1.0)
(stat_comp_benchmarks/benchmarks/low_dim_corr_gauss/low_dim_corr_gauss.stan, 0.97)
(stat_comp_benchmarks/benchmarks/irt_2pl/irt_2pl.stan, 0.99)
(stat_comp_benchmarks/benchmarks/pkpd/one_comp_mm_elim_abs.stan, 1.03)
(stat_comp_benchmarks/benchmarks/eight_schools/eight_schools.stan, 0.99)
(stat_comp_benchmarks/benchmarks/gp_regr/gp_regr.stan, 1.0)
(stat_comp_benchmarks/benchmarks/arK/arK.stan, 0.99)
(performance.compilation, 1.01)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan, 1.0)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix/low_dim_gauss_mix.stan, 1.0)
(stat_comp_benchmarks/benchmarks/sir/sir.stan, 0.99)
(stat_comp_benchmarks/benchmarks/pkpd/sim_one_comp_mm_elim_abs.stan, 1.0)
(stat_comp_benchmarks/benchmarks/garch/garch.stan, 1.0)
(stat_comp_benchmarks/benchmarks/gp_regr/gen_gp_data.stan, 0.99)
(stat_comp_benchmarks/benchmarks/arma/arma.stan, 0.99)
Result: 0.99780328291
Commit hash: 7d956b9

[bob-carpenter]

Thanks. Looks good. I left a comment, but it's not worth waiting for, so I'll just merge.

[bob-carpenter]

This wasn't quite ready. It needs copyright holder information added to the text of the PR.

[mcol]

Thanks for the suggestion, I didn't know about the nullary constructor! I've now edited the PR with the copyright holder info.

[bob-carpenter]

They're both technically calling the nullary constructor. The brace constructor return works for any constructor signature. For instance, return {0, 0}; would've also worked by calling the binary constructor Matrix<T, -1, -1>(0, 0), which is equivalent to Matrix<T, -1, -1>(). This works for assignment and return is just a special kind of assignment. All four of these have the same effect: Matrix<T, -1, -1> m{2, 2}; Matrix<T, -1, -1> m(2, 2); Matrix<T, -1, -1> m = {2, 2}; Matrix<T, -1, -1> m = Matrix<T, -1, -1>(2, 2); The direct construction will be at least as efficient as there's no copy (with move semantics, the assignment can now be as efficient, but I don't think Eigen supports && constructors or assignments yet).

…

On Nov 18, 2019, at 12:51 PM, Marco Colombo ***@***.***> wrote: Thanks for the suggestion, I didn't know about the nullary constructor! I've now edited the PR with the copyright holder info. — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.

[stan-buildbot]

(stat_comp_benchmarks/benchmarks/gp_pois_regr/gp_pois_regr.stan, 0.99)
(stat_comp_benchmarks/benchmarks/low_dim_corr_gauss/low_dim_corr_gauss.stan, 1.01)
(stat_comp_benchmarks/benchmarks/irt_2pl/irt_2pl.stan, 1.0)
(stat_comp_benchmarks/benchmarks/pkpd/one_comp_mm_elim_abs.stan, 1.01)
(stat_comp_benchmarks/benchmarks/eight_schools/eight_schools.stan, 1.02)
(stat_comp_benchmarks/benchmarks/gp_regr/gp_regr.stan, 0.99)
(stat_comp_benchmarks/benchmarks/arK/arK.stan, 1.0)
(performance.compilation, 1.01)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan, 1.01)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix/low_dim_gauss_mix.stan, 1.0)
(stat_comp_benchmarks/benchmarks/sir/sir.stan, 1.0)
(stat_comp_benchmarks/benchmarks/pkpd/sim_one_comp_mm_elim_abs.stan, 1.0)
(stat_comp_benchmarks/benchmarks/garch/garch.stan, 1.0)
(stat_comp_benchmarks/benchmarks/gp_regr/gen_gp_data.stan, 1.0)
(stat_comp_benchmarks/benchmarks/arma/arma.stan, 1.01)
Result: Regex did not match anything
Commit hash: 93226e2