diff --git a/lesson7/gonum/mat21.go b/lesson7/gonum/mat21.go
new file mode 100644
index 0000000..4d08645
--- /dev/null
+++ b/lesson7/gonum/mat21.go
@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+	"gonum.org/v1/gonum/mat"
+)
+
+func main() {
+	v := mat.NewSymDense(3, nil)
+	fmt.Printf("Value:\n%v\n\n", mat.Formatted(v))
+
+	cap1, cap2 := v.Caps()
+	fmt.Printf("Capacity:   %dx%d\n", cap1, cap2)
+
+	dim1, dim2 := v.Dims()
+	fmt.Printf("Dimensions: %dx%d\n", dim1, dim2)
+}