new file mode 100644
--- /dev/null
+++ b/volume_io/Testing/test_newton.c
@@ -0,0 +1,41 @@
+#include  <internal_volume_io.h>
+
+private      void   function(
+    Real   parameters[],
+    Real   values[],
+    Real   **derivatives );
+
+int main(
+    int   argc,
+    char  *argv[] )
+{
+    int    n_dims = 1, arg;
+    Real   x, desired, solution, actual, **deriv;
+
+    arg = 1;
+    if( arg >= argc || sscanf( argv[arg++], "%lf", &x ) != 1 )
+        x = 0.0;
+    if( arg >= argc || sscanf( argv[arg++], "%lf", &desired ) != 1 )
+        desired = 0.0;
+
+    ALLOC2D( deriv, n_dims, n_dims );
+
+    if( invert_function( 1, &function, &x, &desired, &solution, 1e-3, 1000 ) )
+    {
+        function( &solution, &actual, deriv );
+        print( "Solution: %g = %g\n", solution, actual );
+    }
+
+    FREE2D( deriv );
+
+    return( 0 );
+}
+
+private      void   function(
+    Real   parameters[],
+    Real   values[],
+    Real   **derivatives )
+{
+    values[0] = 20.0 - parameters[0] * 9.0 + parameters[0] * parameters[0];
+    derivatives[0][0] = 9.0 + 2.0 * parameters[0];
+}