Minor fixes for hypergeometric 1F0 and 2F1

[andrjohns]

Summary

As pointed out in the stanc3 repo, the hypergeometric 1F0 function naming is inconsistent with the others - using a lowercase 'f' (i.e., hypergeometric_1f0 instead of hypergeometric_1F0)

Additionally, hypergeometric_2F1 fails to compile if the second argument is an autodiff type but not the others

Tests

N/A - existing tests should still pass

Side Effects

N/A

Release notes

Renamed hypergeometric_1f0 to hypergeometric_1F0 for consistency, fixed compilation for hypergeometric_2f1 with autodiff second argument

Checklist

• Copyright holder: Andrew Johnson

  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

[andrjohns]

Just rolled the 2F1 fixes into this PR as well instead of making a separate one

[WardBrian]

Not sure if you want to look at it here, but hypergeometric_3F2 is unhappy if given a row_vector -- vector and array[] real are fine, but row_vector raises an error on the line append_row(as_array_or_scalar(b), 1.0);

By contrast, hypergeometric_pFq is happy with vector and row_vector but not array[] real (no matching function call...).

Neither of these are strictly necessary for exposing in the language, but if we want consistency they'd be nice to address

[WardBrian]

@andrjohns the rev specialization of hypergeometric_pFq is failing expression tests, I believe because the line

  auto pfq_val = hypergeometric_pFq(a.val(), b.val(), value_of(z));

should be

  auto pfq_val = hypergeometric_pFq(arena_a.val(), arena_b.val(), value_of(z));

[WardBrian]

This can go in as is (assuming you don't want to look at the vector issues mentioned above)

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
arma/arma.stan	0.34	0.32	1.05	5.03% faster
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.01	0.01	1.03	3.15% faster
gp_regr/gen_gp_data.stan	0.03	0.02	1.08	6.99% faster
gp_regr/gp_regr.stan	0.1	0.09	1.1	8.71% faster
sir/sir.stan	72.89	66.46	1.1	8.83% faster
irt_2pl/irt_2pl.stan	4.26	3.89	1.1	8.69% faster
eight_schools/eight_schools.stan	0.06	0.05	1.11	9.6% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.26	0.24	1.09	8.56% faster
pkpd/one_comp_mm_elim_abs.stan	19.86	18.54	1.07	6.68% faster
garch/garch.stan	0.46	0.4	1.14	12.09% faster
low_dim_gauss_mix/low_dim_gauss_mix.stan	2.83	2.6	1.09	8.22% faster
arK/arK.stan	1.86	1.71	1.09	8.07% faster
gp_pois_regr/gp_pois_regr.stan	2.9	2.68	1.08	7.64% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.92	8.3	1.07	6.91% faster
performance.compilation	196.6	191.53	1.03	2.58% faster
Mean result: 1.0811679718034342

---

Jenkins Console Log
Blue Ocean
Commit hash: 7d96cffaf504f2fc7cd2541038f6d115e49c3e9d

---

Machine information

No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 20.04.3 LTS Release: 20.04 Codename: focal

CPU:
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 46 bits physical, 48 bits virtual
CPU(s): 80
On-line CPU(s) list: 0-79
Thread(s) per core: 2
Core(s) per socket: 20
Socket(s): 2
NUMA node(s): 2
Vendor ID: GenuineIntel
CPU family: 6
Model: 85
Model name: Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
Stepping: 4
CPU MHz: 2400.000
CPU max MHz: 3700.0000
CPU min MHz: 1000.0000
BogoMIPS: 4800.00
Virtualization: VT-x
L1d cache: 1.3 MiB
L1i cache: 1.3 MiB
L2 cache: 40 MiB
L3 cache: 55 MiB
NUMA node0 CPU(s): 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78
NUMA node1 CPU(s): 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79
Vulnerability Gather data sampling: Mitigation; Microcode
Vulnerability Itlb multihit: KVM: Mitigation: VMX disabled
Vulnerability L1tf: Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown: Mitigation; PTI
Vulnerability Mmio stale data: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed: Mitigation; IBRS
Vulnerability Spec rstack overflow: Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2: Mitigation; IBRS; IBPB conditional; STIBP conditional; RSB filling; PBRSB-eIBRS Not affected; BHI Not affected
Vulnerability Srbds: Not affected
Vulnerability Tsx async abort: Mitigation; Clear CPU buffers; SMT vulnerable
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single pti intel_ppin ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req pku ospke md_clear flush_l1d arch_capabilities

G++:
g++ (Ubuntu 9.4.0-1ubuntu1~20.04) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Clang:
clang version 10.0.0-4ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

[andrjohns]

This can go in as is (assuming you don't want to look at the vector issues mentioned above)

The vector issues were pretty simple fixes, so I've just added them as well

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
arma/arma.stan	0.33	0.31	1.08	7.76% faster
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.01	0.01	1.13	11.45% faster
gp_regr/gen_gp_data.stan	0.03	0.02	1.07	6.35% faster
gp_regr/gp_regr.stan	0.1	0.09	1.12	10.37% faster
sir/sir.stan	70.95	66.93	1.06	5.67% faster
irt_2pl/irt_2pl.stan	4.3	3.95	1.09	8.14% faster
eight_schools/eight_schools.stan	0.06	0.06	1.04	4.19% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.26	0.24	1.06	5.49% faster
pkpd/one_comp_mm_elim_abs.stan	20.2	18.72	1.08	7.3% faster
garch/garch.stan	0.46	0.4	1.15	13.42% faster
low_dim_gauss_mix/low_dim_gauss_mix.stan	2.83	2.58	1.1	8.77% faster
arK/arK.stan	1.89	1.7	1.11	10.06% faster
gp_pois_regr/gp_pois_regr.stan	2.86	2.66	1.07	6.7% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.95	8.4	1.07	6.13% faster
performance.compilation	180.27	181.42	0.99	-0.64% slower
Mean result: 1.0813312271880846

---

Jenkins Console Log
Blue Ocean
Commit hash: 7d96cffaf504f2fc7cd2541038f6d115e49c3e9d

---

Machine information

No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 20.04.3 LTS Release: 20.04 Codename: focal

CPU:
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 46 bits physical, 48 bits virtual
CPU(s): 80
On-line CPU(s) list: 0-79
Thread(s) per core: 2
Core(s) per socket: 20
Socket(s): 2
NUMA node(s): 2
Vendor ID: GenuineIntel
CPU family: 6
Model: 85
Model name: Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
Stepping: 4
CPU MHz: 2400.000
CPU max MHz: 3700.0000
CPU min MHz: 1000.0000
BogoMIPS: 4800.00
Virtualization: VT-x
L1d cache: 1.3 MiB
L1i cache: 1.3 MiB
L2 cache: 40 MiB
L3 cache: 55 MiB
NUMA node0 CPU(s): 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78
NUMA node1 CPU(s): 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79
Vulnerability Gather data sampling: Mitigation; Microcode
Vulnerability Itlb multihit: KVM: Mitigation: VMX disabled
Vulnerability L1tf: Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown: Mitigation; PTI
Vulnerability Mmio stale data: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed: Mitigation; IBRS
Vulnerability Spec rstack overflow: Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2: Mitigation; IBRS; IBPB conditional; STIBP conditional; RSB filling; PBRSB-eIBRS Not affected; BHI Not affected
Vulnerability Srbds: Not affected
Vulnerability Tsx async abort: Mitigation; Clear CPU buffers; SMT vulnerable
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single pti intel_ppin ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req pku ospke md_clear flush_l1d arch_capabilities

G++:
g++ (Ubuntu 9.4.0-1ubuntu1~20.04) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Clang:
clang version 10.0.0-4ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

[WardBrian]

@andrjohns I think the (hopefully) last thing is that hypergeometric_3F2 isn't expression safe (does a sum and a to_vector, both of which will eval) and also does indexing into a and b without first checking their sizes. So it needs a little TLC, and probably also an entry in the special_arg_values list (unless it just can't be called with length-1 vectors, in which case we need to skip it?)

[WardBrian]

Would it make sense if something like 3F2 had a signature (tuple(real, real, real), tuple(real, real)) => real instead of/as well as the current signature which takes a vector and just assumes the length?

[WardBrian]

The vector issues were pretty simple fixes, so I've just added them as well

It looks like this change missed the rev overload, which also seems to require some template changes to grad_pFq to compile with std::vectors

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
arma/arma.stan	0.36	0.31	1.15	13.09% faster
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.01	0.01	1.09	8.25% faster
gp_regr/gen_gp_data.stan	0.03	0.02	1.08	7.25% faster
gp_regr/gp_regr.stan	0.1	0.09	1.12	10.68% faster
sir/sir.stan	71.57	66.51	1.08	7.08% faster
irt_2pl/irt_2pl.stan	4.16	3.98	1.05	4.41% faster
eight_schools/eight_schools.stan	0.06	0.05	1.03	3.15% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.25	0.24	1.05	4.76% faster
pkpd/one_comp_mm_elim_abs.stan	20.11	18.7	1.08	7.04% faster
garch/garch.stan	0.45	0.41	1.1	8.89% faster
low_dim_gauss_mix/low_dim_gauss_mix.stan	2.76	2.63	1.05	4.76% faster
arK/arK.stan	1.82	1.73	1.05	5.09% faster
gp_pois_regr/gp_pois_regr.stan	2.87	2.69	1.06	5.99% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.84	8.43	1.05	4.65% faster
performance.compilation	181.89	180.77	1.01	0.61% faster
Mean result: 1.069236081869054

---

Jenkins Console Log
Blue Ocean
Commit hash: 7d96cffaf504f2fc7cd2541038f6d115e49c3e9d

---

Machine information

No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 20.04.3 LTS Release: 20.04 Codename: focal

CPU:
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 46 bits physical, 48 bits virtual
CPU(s): 80
On-line CPU(s) list: 0-79
Thread(s) per core: 2
Core(s) per socket: 20
Socket(s): 2
NUMA node(s): 2
Vendor ID: GenuineIntel
CPU family: 6
Model: 85
Model name: Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
Stepping: 4
CPU MHz: 2400.000
CPU max MHz: 3700.0000
CPU min MHz: 1000.0000
BogoMIPS: 4800.00
Virtualization: VT-x
L1d cache: 1.3 MiB
L1i cache: 1.3 MiB
L2 cache: 40 MiB
L3 cache: 55 MiB
NUMA node0 CPU(s): 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78
NUMA node1 CPU(s): 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79
Vulnerability Gather data sampling: Mitigation; Microcode
Vulnerability Itlb multihit: KVM: Mitigation: VMX disabled
Vulnerability L1tf: Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown: Mitigation; PTI
Vulnerability Mmio stale data: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed: Mitigation; IBRS
Vulnerability Spec rstack overflow: Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2: Mitigation; IBRS; IBPB conditional; STIBP conditional; RSB filling; PBRSB-eIBRS Not affected; BHI Not affected
Vulnerability Srbds: Not affected
Vulnerability Tsx async abort: Mitigation; Clear CPU buffers; SMT vulnerable
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single pti intel_ppin ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req pku ospke md_clear flush_l1d arch_capabilities

G++:
g++ (Ubuntu 9.4.0-1ubuntu1~20.04) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Clang:
clang version 10.0.0-4ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

[andrjohns]

@andrjohns I think the (hopefully) last thing is that hypergeometric_3F2 isn't expression safe (does a sum and a to_vector, both of which will eval) and also does indexing into a and b without first checking their sizes. So it needs a little TLC, and probably also an entry in the special_arg_values list (unless it just can't be called with length-1 vectors, in which case we need to skip it?)

We probably don't need to expose both pFq and 3F2 tbh. The only extra thing in 3F2 is manual handling of a particular case which doesn't meet convergence criteria but numerically converges that was already in the tests, so I'd consider that more of an edge case.

[WardBrian]

Fine by me, though if it’s easy enough there’s no reason to not add them I guess. Do you have a chance to look at rev/fwd for pFq with the vector changes?