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Clarified wording #8197

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0b9da1e
Clarified wording
athakur6-lgtm Mar 15, 2026
068355e
removed wishart warning
athakur6-lgtm Mar 21, 2026
d52e5d0
Merge branch 'v6' into wishart_docs_fix
anikat2 Mar 21, 2026
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17 changes: 5 additions & 12 deletions pymc/distributions/multivariate.py
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Original file line number Diff line number Diff line change
Expand Up @@ -998,8 +998,11 @@ class Wishart(Continuous):

Notes
-----
This distribution is unusable in a PyMC model. You should instead
use LKJCholeskyCov or LKJCorr.
This distribution is not recommended as a prior distribution for MCMC
sampling. Most samplers operate in unconstrained space and proposals
rarely satisfy the symmetric positive definite constraint, causing
sampling to fail or perform poorly. Consider using LKJCholeskyCov or
LKJCorr instead.
"""

rv_op = wishart
Expand All @@ -1009,16 +1012,6 @@ def dist(cls, nu, V, *args, **kwargs):
nu = pt.as_tensor_variable(nu, dtype=int)
V = pt.as_tensor_variable(V)

warnings.warn(
"The Wishart distribution can currently not be used "
"for MCMC sampling. The probability of sampling a "
"symmetric matrix is basically zero. Instead, please "
"use LKJCholeskyCov or LKJCorr. For more information "
"on the issues surrounding the Wishart see here: "
"https://github.com/pymc-devs/pymc/issues/538.",
UserWarning,
)

# mean = nu * V
# p = V.shape[0]
# mode = pt.switch(pt.ge(nu, p + 1), (nu - p - 1) * V, np.nan)
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