Improved error message in case not possible to create a file

C-Sources/ModelicaIO.c

@@ -320,13 +320,18 @@ MODELICA_EXPORT int ModelicaIO_writeRealMatrix(const char* fileName,
         matc = MAT_COMPRESSION_NONE;
     }
 
-    mat = append == 0 ?
-        Mat_CreateVer(fileName, NULL, matv) :
-        Mat_Open(fileName, (int)MAT_ACC_RDWR | matv);
-
-    if (mat == NULL) {
-        ModelicaFormatError("Not possible to open file \"%s\"\n", fileName);
-        return 0;
+    if ( append == 0 ) {
+        mat = Mat_CreateVer(fileName, NULL, matv);
+        if (mat == NULL) {
+           ModelicaFormatError("Not possible to newly create file \"%s\"\n(maybe version 7.3 not supported)\n", fileName);
+           return 0;
+        }        
+    } else {
+        mat = Mat_Open(fileName, (int)MAT_ACC_RDWR | matv);
+        if (mat == NULL) {
+           ModelicaFormatError("Not possible to open file \"%s\"\n", fileName);         
+           return 0;
+        }
     }
 
     /* MAT file array is stored column-wise -> need to transpose */