Interpolate (#137)

- added eta based interpolation

src/NDArray.test.cpp

@@ -2,6 +2,7 @@
 #include <array>
 #include <catch2/benchmark/catch_benchmark.hpp>
 #include <catch2/catch_test_macros.hpp>
+#include <numeric>
 
 using aare::NDArray;
 using aare::NDView;
@@ -34,6 +35,24 @@ TEST_CASE("Construct from an NDView") {
     }
 }
 
+TEST_CASE("3D NDArray from NDView"){
+    std::vector<int> data(27);
+    std::iota(data.begin(), data.end(), 0);
+    NDView<int, 3> view(data.data(), Shape<3>{3, 3, 3});
+    NDArray<int, 3> image(view);
+    REQUIRE(image.shape() == view.shape());
+    REQUIRE(image.size() == view.size());
+    REQUIRE(image.data() != view.data());
+
+    for(int64_t i=0; i<image.shape(0); i++){
+        for(int64_t j=0; j<image.shape(1); j++){
+            for(int64_t k=0; k<image.shape(2); k++){
+                REQUIRE(image(i, j, k) == view(i, j, k));
+            }
+        }
+    }
+}
+
 TEST_CASE("1D image") {
     std::array<int64_t, 1> shape{{20}};
     NDArray<short, 1> img(shape, 3);