stan-dev/math

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The Stan Math Library is a C++ template library for automatic differentiation of any order using forward, reverse, and mixed modes. It includes a range of built-in functions for probabilistic modeling, linear algebra, and equation solving.

Stars: 839
Forks: 220
Open beginner issues: 0
Indexed issues: 272
Avg merge: 2d 4h
Merged PRs (30d): 14

Dominant language: C++
License: BSD-3-Clause
Last GitHub push: Sep 16, 2026
Latest indexed: Sep 19, 2026
Contributing guide: Contributing guide
Code of conduct: No code of conduct
Beginner labels: good first issue

Beginner friendly Everything

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272 open issues indexed

Cleaning up linear access functions Open

Difficulty 5/5 Over a week Newbie friendliness 20/100

stan-dev/math#2245 · 4 comments · 1 reaction · Opened Dec 7, 2020
`ranef` function for accumulating random effects without getting temporaries Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

stan-dev/math#2237 · 9 comments · Opened Dec 4, 2020
BDF ODE integrator slow Open

Difficulty 4/5 3-5 days Newbie friendliness 30/100

stan-dev/math#2224 · Opened Dec 2, 2020
Address sanitizer warnings in threaded `reduce_sum` Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#2203 · Opened Nov 20, 2020
Return types not being checked for consistency in test framework Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#2198 · Opened Nov 16, 2020
Implement closures Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

stan-dev/math#2197 · 18 comments · Opened Nov 16, 2020
Allowing assignment in `segment' as in `segment(matrix X, a, b) = segment(matrix Y, w, z)` Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#2195 · 3 comments · Opened Nov 15, 2020
Feature request: Expose autocorrelation functions Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#2189 · 1 reaction · Opened Nov 12, 2020
autodiff test framework is not testing first gradients Open

good first issue

Difficulty 2/5 1-3 hours Newbie friendliness 45/100

stan-dev/math#2167 · 1 reaction · Opened Oct 27, 2020
Allow real argument to order of modified_bessel_x_kind Open

code cleanup

Difficulty 5/5 Over a week Newbie friendliness 25/100

stan-dev/math#2153 · 7 comments · Opened Oct 20, 2020
determinant algorithm Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

stan-dev/math#2120 · 18 comments · Opened Oct 1, 2020
operator* does not compile for one input matrix with double and other with var scalars Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

stan-dev/math#2103 · 2 comments · Opened Sep 25, 2020
Make functions with custom autodiff `var<mat>` friendly Open

Difficulty 5/5 Over a week Newbie friendliness 20/100

stan-dev/math#2101 · 7 comments · Opened Sep 24, 2020
Building Google benchmark library in math Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

stan-dev/math#2083 · 2 reactions · Opened Sep 11, 2020
Numerical issues in neg_binomial_lccdf if beta is very large Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

stan-dev/math#2031 · Opened Aug 21, 2020
Simplifying current reverse mode functions Open

code cleanup feature

Difficulty 5/5 Over a week Newbie friendliness 20/100

stan-dev/math#2018 · Opened Aug 18, 2020
gamma_p and gamma_q gradient problems Open

numerics

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#2006 · 5 comments · 1 reaction · Opened Aug 6, 2020
vector distribution tests should test with vectors of not all the same values Open

distributions testing

Difficulty 3/5 1-2 days Newbie friendliness 45/100

stan-dev/math#1978 · 2 comments · Opened Jul 19, 2020
Beta cdf/lcdf/lccdf prob tests wrong Open

distributions testing

Difficulty 3/5 1-2 days Newbie friendliness 45/100

stan-dev/math#1976 · 4 comments · Opened Jul 14, 2020
Re-evaluate ODE default max_num_steps values Open

performance

Difficulty 4/5 3-5 days Newbie friendliness 38/100

stan-dev/math#1969 · Opened Jul 8, 2020
boundaries should be exclusive in positive-constrained distributions like lognormal Open

bug

Difficulty 1/5 1-3 hours Newbie friendliness 55/100

stan-dev/math#1968 · Opened Jul 6, 2020
more glm functions Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

stan-dev/math#1964 · 8 comments · 3 reactions · Opened Jul 6, 2020
structured linear algebra and GP covariance functions Open

feature

Difficulty 5/5 Over a week Newbie friendliness 20/100

stan-dev/math#1960 · 1 comment · 3 reactions · Opened Jul 1, 2020
ODE stress test Open

testing

Difficulty 4/5 3-5 days Newbie friendliness 42/100

stan-dev/math#1956 · Opened Jul 1, 2020
Possible performance issue: cov_matrix_constrain works in row-order on a column-major matrix Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

stan-dev/math#1954 · 6 comments · 1 reaction · Opened Jun 30, 2020
Use TBB to parallelise unary functions of large containers Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

stan-dev/math#1918 · 99 comments · 3 reactions · Opened Jun 4, 2020
specialized triangular inverse Open

feature good first issue new function

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1911 · Opened May 25, 2020
Manual documentation for mdivide_* Open

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

stan-dev/math#1897 · 4 comments · Opened May 19, 2020
Size behavior is not consistent for function arguments Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

stan-dev/math#1835 · 2 comments · Opened Apr 13, 2020
Wrong derivatives for cholesky and symmetric eigen decomposition Open

bug

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1803 · 17 comments · 3 reactions · Opened Mar 28, 2020
clean up doxygen errors introduced by new metaprograms Open

bug code cleanup doc

stan-dev/math#1793 · 7 comments · 1 assignee · Opened Mar 23, 2020
autodiff for matrix add and subtract Open

code cleanup feature

Difficulty 4/5 3-5 days Newbie friendliness 25/100

stan-dev/math#1787 · 5 comments · 1 reaction · Opened Mar 20, 2020
change check behavior to only use double types Open

code cleanup performance

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1779 · 2 comments · Opened Mar 13, 2020
update make help to describe everything CI runs & update to newest develop Open

build doc

stan-dev/math#1776 · 3 comments · 1 assignee · Opened Mar 12, 2020
on_scheduler_exit unused Open

code cleanup

Difficulty 3/5 1-2 days Newbie friendliness 35/100

stan-dev/math#1749 · 13 comments · Opened Feb 25, 2020
generalize Eigen NumTraits specializations for decay types Open

feature

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1748 · Opened Feb 25, 2020
relax type identity between constrained variable and target log density Open

code cleanup good first issue

Difficulty 4/5 3-5 days Newbie friendliness 42/100

stan-dev/math#1733 · Opened Feb 21, 2020
domain errors not being thrown by uniform_lpdf, discrete_uniform_lpmf, pareto_lpdf Open

bug code cleanup

Difficulty 3/5 1-2 days Newbie friendliness 35/100

stan-dev/math#1697 · 1 comment · Opened Feb 11, 2020
integer parameters/variates can take real values in density/mass functions Open

code cleanup doc

Difficulty 4/5 3-5 days Newbie friendliness 32/100

stan-dev/math#1696 · 6 comments · Opened Feb 11, 2020
constant standard vector and Eigen matrix initializers Open

code cleanup feature

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1676 · 1 comment · Opened Feb 5, 2020
Tools for testing identitites Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1671 · 11 comments · 1 reaction · Opened Feb 4, 2020
Deeply nested containers and error checks Open

code cleanup feature

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1635 · 7 comments · Opened Jan 20, 2020
The derivatives of neg_binomial_lpmf are incorrect for large alpha Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1578 · Opened Jan 3, 2020
inc_beta overpromotion Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

stan-dev/math#1570 · 3 comments · Opened Dec 31, 2019
Some expect_ad calls fail to compile Open

testing

Difficulty 4/5 3-5 days Newbie friendliness 42/100

stan-dev/math#1533 · 2 comments · Opened Dec 20, 2019
get rid of the ::value in include_summand<propto, T1, ..., TN>::value Open

code cleanup

Difficulty 3/5 1-2 days Newbie friendliness 45/100

stan-dev/math#1521 · 5 comments · Opened Dec 15, 2019
GLM functions are missing forward tests Open

testing

stan-dev/math#1501 · 1 assignee · Opened Dec 11, 2019
map_rect with fixed integer and real data across shards Open

feature

Difficulty 5/5 Over a week Newbie friendliness 35/100

stan-dev/math#1494 · 5 comments · Opened Dec 8, 2019
Inconsistent error handling Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

stan-dev/math#1468 · 15 comments · Opened Nov 28, 2019
Extend gaussian_dlm_obs to allow time-varying system matrices Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

stan-dev/math#1466 · 1 comment · 1 reaction · Opened Nov 26, 2019

stan-dev/math

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