Have conditional_var_value_t return correct matrix type if scalar is var

[SteveBronder]

Summary

This just makes conditional_var_value_t<var, Eigen::Matrix<var, -1, -1>> returns back a var_value<Eigen::Matrix<double, -1, -1>>

Tests

Test added for checking above behavior

./runTests.py ./test/unit/math/rev/meta/conditional_var_value_test.cpp

Side Effects

Nope

Release notes

Fixes case for conditional_var_value_t

Checklist

• Math issue How to add static matrix? #1805

• Copyright holder: (fill in copyright holder information)

  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)
  • dependencies checks pass, (make test-math-dependencies)
  • 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]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	3.12	3.09	1.01	0.97% faster
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.02	0.02	0.99	-0.83% slower
eight_schools/eight_schools.stan	0.12	0.12	0.97	-2.77% slower
gp_regr/gp_regr.stan	0.16	0.16	1.01	1.29% faster
irt_2pl/irt_2pl.stan	6.03	6.07	0.99	-0.66% slower
performance.compilation	88.59	87.56	1.01	1.17% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.74	8.69	1.01	0.58% faster
pkpd/one_comp_mm_elim_abs.stan	30.29	29.28	1.03	3.31% faster
sir/sir.stan	148.84	140.35	1.06	5.7% faster
gp_regr/gen_gp_data.stan	0.03	0.03	1.01	1.27% faster
low_dim_gauss_mix/low_dim_gauss_mix.stan	3.02	3.01	1.0	0.28% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.41	0.38	1.06	5.51% faster
arK/arK.stan	1.88	1.88	1.0	0.14% faster
arma/arma.stan	0.65	0.65	1.0	-0.48% slower
garch/garch.stan	0.68	0.7	0.98	-2.14% slower
Mean result: 1.0095402771

---

Jenkins Console Log
Blue Ocean
Commit hash: c8a67fc

---

Machine information

ProductName: Mac OS X ProductVersion: 10.11.6 BuildVersion: 15G22010

CPU:
Intel(R) Xeon(R) CPU E5-1680 v2 @ 3.00GHz

G++:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

Clang:
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

[t4c1]

Fix the doxygen according to the change.

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	3.15	3.12	1.01	1.01% faster
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.02	0.02	1.0	0.36% faster
eight_schools/eight_schools.stan	0.11	0.12	0.97	-3.3% slower
gp_regr/gp_regr.stan	0.16	0.16	1.01	0.96% faster
irt_2pl/irt_2pl.stan	6.0	6.02	1.0	-0.34% slower
performance.compilation	89.72	87.45	1.03	2.53% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.77	8.74	1.0	0.34% faster
pkpd/one_comp_mm_elim_abs.stan	30.23	29.08	1.04	3.81% faster
sir/sir.stan	138.22	144.61	0.96	-4.62% slower
gp_regr/gen_gp_data.stan	0.03	0.04	0.98	-1.61% slower
low_dim_gauss_mix/low_dim_gauss_mix.stan	3.04	3.08	0.99	-1.38% slower
pkpd/sim_one_comp_mm_elim_abs.stan	0.41	0.41	0.99	-0.7% slower
arK/arK.stan	1.88	1.86	1.01	0.72% faster
arma/arma.stan	0.64	0.64	0.99	-0.83% slower
garch/garch.stan	0.69	0.67	1.03	3.14% faster
Mean result: 1.00053387

---

Jenkins Console Log
Blue Ocean
Commit hash: 8fbe74a

---

Machine information

ProductName: Mac OS X ProductVersion: 10.11.6 BuildVersion: 15G22010

CPU:
Intel(R) Xeon(R) CPU E5-1680 v2 @ 3.00GHz

G++:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

Clang:
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	3.09	3.12	0.99	-1.17% slower
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.02	0.02	0.98	-1.59% slower
eight_schools/eight_schools.stan	0.11	0.12	0.98	-2.33% slower
gp_regr/gp_regr.stan	0.17	0.17	0.99	-0.82% slower
irt_2pl/irt_2pl.stan	6.05	5.99	1.01	1.01% faster
performance.compilation	88.42	87.12	1.01	1.47% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.73	8.72	1.0	0.12% faster
pkpd/one_comp_mm_elim_abs.stan	29.51	30.2	0.98	-2.32% slower
sir/sir.stan	137.39	150.86	0.91	-9.81% slower
gp_regr/gen_gp_data.stan	0.04	0.04	0.98	-2.49% slower
low_dim_gauss_mix/low_dim_gauss_mix.stan	3.11	3.01	1.03	3.0% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.39	0.4	0.97	-3.23% slower
arK/arK.stan	1.85	1.85	1.0	-0.07% slower
arma/arma.stan	0.64	0.64	1.01	1.06% faster
garch/garch.stan	0.68	0.67	1.01	0.62% faster
Mean result: 0.989847083507

---

Jenkins Console Log
Blue Ocean
Commit hash: 0034da2

---

Machine information

ProductName: Mac OS X ProductVersion: 10.11.6 BuildVersion: 15G22010

CPU:
Intel(R) Xeon(R) CPU E5-1680 v2 @ 3.00GHz

G++:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

Clang:
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

[SteveBronder]

@rok-cesnovar is it fine to merge this? It's a bug fix

[rok-cesnovar]

Yeah, bugfixes are good.