diff --git a/src/core/array_ex.cpp b/src/core/array_ex.cpp
index 001f53a..c6b4ded 100644
--- a/src/core/array_ex.cpp
+++ b/src/core/array_ex.cpp
@@ -38,57 +38,28 @@ double get_x(const point3dc &p)
 int main(int argc, char const *argv[]) try
 {
 	// create a new array and give initial values
-	array<double> A(10, 0.0, 1.0);
-	A.memory_usage();
+	array<double> a(10, 1.0);
+	array<double> b(10, 2.0);
+	a.show();
+	std::cout << b << "\n";
 
-	A.log2linear(2);
-	A.show();
+	if (a != b) std::cout << "a != b\n";
 
-	A.linear2log(2);
-	A.show();
+	array<double> c;
+	c = a + b; c.show();
+	c = a - b; c.show();
+	c = b - a; c.show();
+	c = a * b; c.show();
+	c = a / b; c.show();
+	c = b / a; c.show();
 
-	A.for_each([](double &a){a += 1;});
-	A.show();
-
-	A.sequence(1.0, 0.5, 3, 4, 1);
-	A.show();
-
-	// copy A to a new array
-	array<double> B = A;
-	B.normalize();
-	B.show();
-
-	array<double> S = A + B;
-	std::cout << "B + A = ";
-	S.show();
-
-	S.normalize();
-	S.show();
-
-	array<point3dc> P(5);
-	P.sequence(point3dc(0, 0, 0), point3dc(2, 1, 0.5));
-	P.show(std::cout, '\n');
-
-	//array<double> Px = P.extract<double>([](const point3dc &p)->double{return p.x;});
-	array<double> Px = P.extract<double>(get_x);
-	Px.show();
-
-	// create a new 2D array
-	matrix<int> C(5, 5, 1);
-	C.sequence(0, 1, 10);
-
-	std::cout << "C = \n";
-	C.show();
-
-	// save array to a binary file
-	save_matrix2binary("tmp/array_ex_out", C, "Int");
-
-	// import 2D array to a new object
-	matrix<int> D;
-	read_binary2matrix("tmp/array_ex_out", D);
-
-	std::cout << "D = \n";
-	D.show();
+	double s = 3.0;
+	c = a + s; c.show();
+	c = a - s; c.show();
+	c = s - a; c.show();
+	c = a * s; c.show();
+	c = a / s; c.show();
+	c = s / a; c.show();
 	return 0;
 }
 catch(std::exception &e)
diff --git a/src/core/fft2d_ex.cpp b/src/core/fft2d_ex.cpp
index 91e582d..2dbe915 100644
--- a/src/core/fft2d_ex.cpp
+++ b/src/core/fft2d_ex.cpp
@@ -128,7 +128,8 @@ int main(int argc, char const *argv[]) try
     }
 
     _1d_array out_freq, out_power, out_std;
-    out_freq.resize(150, 1.0, 1.0);
+    out_freq.resize(150);
+    out_freq.sequence(1.0, 1.0);
     average_radian_spec(pro_freq, pro_spec, out_freq, out_power, out_std);
 
     std::ofstream ofile;
diff --git a/src/core/linear_algebra_ex.cpp b/src/core/linear_algebra_ex.cpp
index 977649a..22b92e9 100644
--- a/src/core/linear_algebra_ex.cpp
+++ b/src/core/linear_algebra_ex.cpp
@@ -31,8 +31,9 @@ using namespace gctl;
 
 int main(int argc, char const *argv[])
 {
-    _1d_array a(10, 1.0, 0.1);
+    _1d_array a(10);
     _1d_array b(10, 1.0);
+    a.sequence(1.0, 1.0);
 
     _1d_array c(10);
     veccpy(c, a, 2.0);
diff --git a/src/core/multinary_ex.cpp b/src/core/multinary_ex.cpp
index a5a9e67..abde5d8 100644
--- a/src/core/multinary_ex.cpp
+++ b/src/core/multinary_ex.cpp
@@ -39,7 +39,8 @@ int main(int argc, char const *argv[]) try
     //array<double> xs = {-2.2, -1.8, -1.5, -1.0, -0.7, -0.2, 0.9, 1.3, 1.9, 2.5};
     //ml.init(xs, std); 
     
-    array<double> x(201, 0.1, 0.001);
+    array<double> x(201);
+    x.sequence(0.1, 0.001);
 
     for (size_t i = 0; i < x.size(); i++)
     {