From dd8bf7553d51f5e7c13e6a086aafa3a3bc8ef3b6 Mon Sep 17 00:00:00 2001
From: Davis King <davis@dlib.net>
Date: Sat, 11 Jun 2016 21:15:04 -0400
Subject: [PATCH] Adjusted asserts to allow mat() to output empty matrices.

---
 dlib/matrix/matrix_mat.h          |  8 ++++----
 dlib/matrix/matrix_mat_abstract.h | 10 +++++-----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/dlib/matrix/matrix_mat.h b/dlib/matrix/matrix_mat.h
index f2c9b46aa..defc22644 100644
--- a/dlib/matrix/matrix_mat.h
+++ b/dlib/matrix/matrix_mat.h
@@ -301,9 +301,9 @@ namespace dlib
         long nr
     )
     {
-        DLIB_ASSERT(nr > 0 , 
+        DLIB_ASSERT(nr >= 0 , 
                     "\tconst matrix_exp mat(ptr, nr)"
-                    << "\n\t nr must be bigger than 0"
+                    << "\n\t nr must be >= 0"
                     << "\n\t nr: " << nr
         );
         typedef op_pointer_to_col_vect<T> op;
@@ -409,9 +409,9 @@ namespace dlib
         long nc
     )
     {
-        DLIB_ASSERT(nr > 0 && nc > 0 , 
+        DLIB_ASSERT(nr >= 0 && nc >= 0 , 
                     "\tconst matrix_exp mat(ptr, nr, nc)"
-                    << "\n\t nr and nc must be bigger than 0"
+                    << "\n\t nr and nc must be >= 0"
                     << "\n\t nr: " << nr
                     << "\n\t nc: " << nc
         );
diff --git a/dlib/matrix/matrix_mat_abstract.h b/dlib/matrix/matrix_mat_abstract.h
index 87d6c1b90..8903f5c33 100644
--- a/dlib/matrix/matrix_mat_abstract.h
+++ b/dlib/matrix/matrix_mat_abstract.h
@@ -114,8 +114,8 @@ namespace dlib
     );
     /*!
         requires
-            - nr > 0
-            - ptr == a pointer to at least nr T objects
+            - nr >= 0
+            - ptr == a pointer to at least nr T objects (or the NULL pointer if nr==0)
         ensures
             - returns a matrix M such that:
                 - M.nr() == nr
@@ -138,9 +138,9 @@ namespace dlib
     );
     /*!
         requires
-            - nr > 0
-            - nc > 0
-            - ptr == a pointer to at least nr*nc T objects
+            - nr >= 0
+            - nc >= 0
+            - ptr == a pointer to at least nr*nc T objects (or the NULL pointer if nr*nc==0)
         ensures
             - returns a matrix M such that:
                 - M.nr() == nr