add BLAS dependency in FindSuperLU.cmake

cmake/FindSuperLU.cmake

diff --git a/cmake/FindSuperLU.cmake b/cmake/FindSuperLU.cmake
index 7383754..e10561b 100644
--- a/cmake/FindSuperLU.cmake
+++ b/cmake/FindSuperLU.cmake
@@ -3,19 +3,29 @@
   set(SUPERLU_FIND_QUIETLY TRUE)
 endif (SUPERLU_INCLUDES AND SUPERLU_LIBRARIES)
 
-find_path(SUPERLU_INCLUDES
-  NAMES
-  superlu/supermatrix.h
-  PATHS
-  $ENV{SUPERLUDIR}
-  ${INCLUDE_INSTALL_DIR}
-)
+find_package(BLAS)
 
-find_library(SUPERLU_LIBRARIES superlu PATHS $ENV{SUPERLUDIR} ${LIB_INSTALL_DIR})
+if(BLAS_FOUND)
+  
+  find_path(SUPERLU_INCLUDES
+    NAMES
+    superlu/supermatrix.h
+    PATHS
+    $ENV{SUPERLUDIR}
+    ${INCLUDE_INSTALL_DIR}
+  )
 
-if(SUPERLU_LIBRARIES AND CMAKE_COMPILER_IS_GNUCXX)
-  set(SUPERLU_LIBRARIES ${SUPERLU_LIBRARIES} -lgfortran)
-endif(SUPERLU_LIBRARIES AND CMAKE_COMPILER_IS_GNUCXX)
+  find_library(SUPERLU_LIBRARIES superlu PATHS $ENV{SUPERLUDIR} ${LIB_INSTALL_DIR})
+
+  if(SUPERLU_LIBRARIES AND CMAKE_COMPILER_IS_GNUCXX)
+    set(SUPERLU_LIBRARIES ${SUPERLU_LIBRARIES} -lgfortran)
+  endif(SUPERLU_LIBRARIES AND CMAKE_COMPILER_IS_GNUCXX)
+  
+  if(SUPERLU_LIBRARIES)
+    set(SUPERLU_LIBRARIES ${SUPERLU_LIBRARIES} ${BLAS_LIBRARIES})
+  endif(SUPERLU_LIBRARIES)
+  
+endif(BLAS_FOUND)
 
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(SUPERLU DEFAULT_MSG