From af3656d4cafd09223f459ab45c9ccd88dc4c07dd Mon Sep 17 00:00:00 2001
From: Alexey Frunze <afrunze@wavecomp.com>
Date: Fri, 31 Aug 2018 14:11:10 -0700
Subject: [PATCH] Fix build failures in matrix_power and matrix_exponential
 tests.

This fixes the static assertion complaining about double being
used in place of long double. This happened on MIPS32, where
double and long double have the same type representation.
This can be simulated on x86 as well if we pass -mlong-double-64
to g++.
(grafted from edeee16a16373dbd86ff0a1129e3d94e3c7e93a7
)
---
 unsupported/Eigen/src/MatrixFunctions/MatrixExponential.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/unsupported/Eigen/src/MatrixFunctions/MatrixExponential.h b/unsupported/Eigen/src/MatrixFunctions/MatrixExponential.h
index 85ab3d97c..e5ebbcf23 100644
--- a/unsupported/Eigen/src/MatrixFunctions/MatrixExponential.h
+++ b/unsupported/Eigen/src/MatrixFunctions/MatrixExponential.h
@@ -234,12 +234,13 @@ struct matrix_exp_computeUV<MatrixType, float>
 template <typename MatrixType>
 struct matrix_exp_computeUV<MatrixType, double>
 {
+  typedef typename NumTraits<typename traits<MatrixType>::Scalar>::Real RealScalar;
   template <typename ArgType>
   static void run(const ArgType& arg, MatrixType& U, MatrixType& V, int& squarings)
   {
     using std::frexp;
     using std::pow;
-    const double l1norm = arg.cwiseAbs().colwise().sum().maxCoeff();
+    const RealScalar l1norm = arg.cwiseAbs().colwise().sum().maxCoeff();
     squarings = 0;
     if (l1norm < 1.495585217958292e-002) {
       matrix_exp_pade3(arg, U, V);
@@ -250,10 +251,10 @@ struct matrix_exp_computeUV<MatrixType, double>
     } else if (l1norm < 2.097847961257068e+000) {
       matrix_exp_pade9(arg, U, V);
     } else {
-      const double maxnorm = 5.371920351148152;
+      const RealScalar maxnorm = 5.371920351148152;
       frexp(l1norm / maxnorm, &squarings);
       if (squarings < 0) squarings = 0;
-      MatrixType A = arg.unaryExpr(MatrixExponentialScalingOp<double>(squarings));
+      MatrixType A = arg.unaryExpr(MatrixExponentialScalingOp<RealScalar>(squarings));
       matrix_exp_pade13(A, U, V);
     }
   }