diff --git a/src/unary.js b/src/unary.js
index 1d45243..8bbb5e1 100644
--- a/src/unary.js
+++ b/src/unary.js
@@ -27,3 +27,4 @@ export const log = (input) => unary(input, Math.log);
 export const neg = (input) => unary(input, (x) => -1 * x);
 export const sin = (input) => unary(input, Math.sin);
 export const tan = (input) => unary(input, Math.tan);
+export const copy = (input) => unary(input, (x) => x);
diff --git a/test/unary_test.js b/test/unary_test.js
index be8899a..3e7a86d 100644
--- a/test/unary_test.js
+++ b/test/unary_test.js
@@ -736,4 +736,65 @@ describe('test unary', function() {
         ],
         [3, 2, 2, 1]);
   });
+
+  it('copy', function() {
+    // 0D scalar
+    testUnary('copy', [1.4124068], [1.4124068], []);
+    testUnary(
+        'copy',
+        [1.4124068, 1.9740626, -0.06506752, 0.73539704],
+        [1.4124068, 1.9740626, -0.06506752, 0.73539704],
+        [4]);
+    testUnary(
+        'copy',
+        [
+          1.4124068,   1.9740626,  -0.06506752, 0.73539704,
+          -0.56439203, 0.89806247, 0.12939146,  -0.34816208,
+          -1.0759926,  0.66291636, 0.21504708,  -0.71527237,
+        ],
+        [
+          1.4124068,   1.9740626,  -0.06506752, 0.73539704,
+          -0.56439203, 0.89806247, 0.12939146,  -0.34816208,
+          -1.0759926,  0.66291636, 0.21504708,  -0.71527237,
+        ],
+        [3, 4]);
+    testUnary(
+        'copy',
+        [
+          1.4124068,   1.9740626,
+          -0.06506752, 0.73539704,
+          -0.56439203, 0.89806247,
+          0.12939146,  -0.34816208,
+          -1.0759926,  0.66291636,
+          0.21504708,  -0.71527237,
+        ],
+        [
+          1.4124068,   1.9740626,
+          -0.06506752, 0.73539704,
+          -0.56439203, 0.89806247,
+          0.12939146,  -0.34816208,
+          -1.0759926,  0.66291636,
+          0.21504708,  -0.71527237,
+        ],
+        [3, 2, 2]);
+    testUnary(
+        'copy',
+        [
+          1.4124068,   1.9740626,
+          -0.06506752, 0.73539704,
+          -0.56439203, 0.89806247,
+          0.12939146,  -0.34816208,
+          -1.0759926,  0.66291636,
+          0.21504708,  -0.71527237,
+        ],
+        [
+          1.4124068,   1.9740626,
+          -0.06506752, 0.73539704,
+          -0.56439203, 0.89806247,
+          0.12939146,  -0.34816208,
+          -1.0759926,  0.66291636,
+          0.21504708,  -0.71527237,
+        ],
+        [3, 2, 2, 1]);
+  });
 });