From ea9123153b712da58a75c064eb75aa5f3806cd90 Mon Sep 17 00:00:00 2001
From: Toshiki Teramura <toshiki.teramura@gmail.com>
Date: Fri, 10 Jul 2020 22:54:44 +0900
Subject: [PATCH 1/2] Impl bk, solveh, and invh using LAPACK

---
 lax/src/solveh.rs | 72 +++++++++++++++++++++++++++++------------------
 1 file changed, 44 insertions(+), 28 deletions(-)

diff --git a/lax/src/solveh.rs b/lax/src/solveh.rs
index 01e90f13..508b2ec6 100644
--- a/lax/src/solveh.rs
+++ b/lax/src/solveh.rs
@@ -5,6 +5,7 @@
 use super::*;
 use crate::{error::*, layout::MatrixLayout};
 use cauchy::*;
+use num_traits::{ToPrimitive, Zero};
 
 pub trait Solveh_: Sized {
     /// Bunch-Kaufman: wrapper of `*sytrf` and `*hetrf`
@@ -28,13 +29,39 @@ macro_rules! impl_solveh {
                 let (n, _) = l.size();
                 let mut ipiv = vec![0; n as usize];
                 if n == 0 {
-                    // Work around bug in LAPACKE functions.
-                    Ok(ipiv)
-                } else {
-                    $trf(l.lapacke_layout(), uplo as u8, n, a, l.lda(), &mut ipiv)
-                        .as_lapack_result()?;
-                    Ok(ipiv)
+                    return Ok(Vec::new());
                 }
+
+                // calc work size
+                let mut info = 0;
+                let mut work_size = [Self::zero()];
+                $trf(
+                    uplo as u8,
+                    n,
+                    a,
+                    l.lda(),
+                    &mut ipiv,
+                    &mut work_size,
+                    -1,
+                    &mut info,
+                );
+                info.as_lapack_result()?;
+
+                // actual
+                let lwork = work_size[0].to_usize().unwrap();
+                let mut work = vec![Self::zero(); lwork];
+                $trf(
+                    uplo as u8,
+                    n,
+                    a,
+                    l.lda(),
+                    &mut ipiv,
+                    &mut work,
+                    lwork as i32,
+                    &mut info,
+                );
+                info.as_lapack_result()?;
+                Ok(ipiv)
             }
 
             unsafe fn invh(
@@ -44,7 +71,10 @@ macro_rules! impl_solveh {
                 ipiv: &Pivot,
             ) -> Result<()> {
                 let (n, _) = l.size();
-                $tri(l.lapacke_layout(), uplo as u8, n, a, l.lda(), ipiv).as_lapack_result()?;
+                let mut info = 0;
+                let mut work = vec![Self::zero(); n as usize];
+                $tri(uplo as u8, n, a, l.lda(), ipiv, &mut work, &mut info);
+                info.as_lapack_result()?;
                 Ok(())
             }
 
@@ -56,30 +86,16 @@ macro_rules! impl_solveh {
                 b: &mut [Self],
             ) -> Result<()> {
                 let (n, _) = l.size();
-                let nrhs = 1;
-                let ldb = match l {
-                    MatrixLayout::C { .. } => 1,
-                    MatrixLayout::F { .. } => n,
-                };
-                $trs(
-                    l.lapacke_layout(),
-                    uplo as u8,
-                    n,
-                    nrhs,
-                    a,
-                    l.lda(),
-                    ipiv,
-                    b,
-                    ldb,
-                )
-                .as_lapack_result()?;
+                let mut info = 0;
+                $trs(uplo as u8, n, 1, a, l.lda(), ipiv, b, n, &mut info);
+                info.as_lapack_result()?;
                 Ok(())
             }
         }
     };
 } // impl_solveh!
 
-impl_solveh!(f64, lapacke::dsytrf, lapacke::dsytri, lapacke::dsytrs);
-impl_solveh!(f32, lapacke::ssytrf, lapacke::ssytri, lapacke::ssytrs);
-impl_solveh!(c64, lapacke::zhetrf, lapacke::zhetri, lapacke::zhetrs);
-impl_solveh!(c32, lapacke::chetrf, lapacke::chetri, lapacke::chetrs);
+impl_solveh!(f64, lapack::dsytrf, lapack::dsytri, lapack::dsytrs);
+impl_solveh!(f32, lapack::ssytrf, lapack::ssytri, lapack::ssytrs);
+impl_solveh!(c64, lapack::zhetrf, lapack::zhetri, lapack::zhetrs);
+impl_solveh!(c32, lapack::chetrf, lapack::chetri, lapack::chetrs);

From 9ccb6af5487f3eae51592a7d49036e2def232fcd Mon Sep 17 00:00:00 2001
From: Toshiki Teramura <toshiki.teramura@gmail.com>
Date: Fri, 10 Jul 2020 22:55:44 +0900
Subject: [PATCH 2/2] Revise deth

---
 ndarray-linalg/src/solveh.rs | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/ndarray-linalg/src/solveh.rs b/ndarray-linalg/src/solveh.rs
index c05e2bde..da748f77 100644
--- a/ndarray-linalg/src/solveh.rs
+++ b/ndarray-linalg/src/solveh.rs
@@ -314,6 +314,7 @@ where
     S: Data<Elem = A>,
     A: Scalar + Lapack,
 {
+    let layout = a.layout().unwrap();
     let mut sign = A::Real::one();
     let mut ln_det = A::Real::zero();
     let mut ipiv_enum = ipiv_iter.enumerate();
@@ -337,9 +338,15 @@ where
             debug_assert_eq!(lower_diag.im(), Zero::zero());
 
             // Off-diagonal elements, can be complex.
-            let off_diag = match uplo {
-                UPLO::Upper => unsafe { a.uget((k, k + 1)) },
-                UPLO::Lower => unsafe { a.uget((k + 1, k)) },
+            let off_diag = match layout {
+                MatrixLayout::C { .. } => match uplo {
+                    UPLO::Upper => unsafe { a.uget((k + 1, k)) },
+                    UPLO::Lower => unsafe { a.uget((k, k + 1)) },
+                },
+                MatrixLayout::F { .. } => match uplo {
+                    UPLO::Upper => unsafe { a.uget((k, k + 1)) },
+                    UPLO::Lower => unsafe { a.uget((k + 1, k)) },
+                },
             };
 
             // Determinant of 2x2 block.