Fix issue with boost::multiprec in previous commit

diff --git a/Eigen/src/SVD/BDCSVD.h b/Eigen/src/SVD/BDCSVD.h
index b440901..0abd4c1 100644
--- a/Eigen/src/SVD/BDCSVD.h
+++ b/Eigen/src/SVD/BDCSVD.h

@@ -845,10 +845,10 @@
       {
         // to avoid overflow, we must have mu > max(real_min, |z(k)|/sqrt(real_max)),
         // the factor 2 is to be more conservative
-        leftShifted = numext::maxi( (std::numeric_limits<RealScalar>::min)(), Literal(2) * abs(col0(k)) / sqrt((std::numeric_limits<RealScalar>::max)()) );
+        leftShifted = numext::maxi<RealScalar>( (std::numeric_limits<RealScalar>::min)(), Literal(2) * abs(col0(k)) / sqrt((std::numeric_limits<RealScalar>::max)()) );
 
         // check that we did it right:
-        eigen_internal_assert( (std::isfinite)( (col0(k)/leftShifted)*(col0(k)/(diag(k)+shift+leftShifted)) ) );
+        eigen_internal_assert( (numext::isfinite)( (col0(k)/leftShifted)*(col0(k)/(diag(k)+shift+leftShifted)) ) );
         // I don't understand why the case k==0 would be special there:
         // if (k == 0) rightShifted = right - left; else
         rightShifted = (k==actual_n-1) ? right : ((right - left) * RealScalar(0.51)); // theoretically we can take 0.5, but let's be safe
@@ -857,7 +857,7 @@
       {
         leftShifted = -(right - left) * RealScalar(0.51);
         if(k+1<n)
-          rightShifted = -numext::maxi( (std::numeric_limits<RealScalar>::min)(), abs(col0(k+1)) / sqrt((std::numeric_limits<RealScalar>::max)()) );
+          rightShifted = -numext::maxi<RealScalar>( (std::numeric_limits<RealScalar>::min)(), abs(col0(k+1)) / sqrt((std::numeric_limits<RealScalar>::max)()) );
         else
           rightShifted = -(std::numeric_limits<RealScalar>::min)();
       }