Documentation of basic use of DenseRange. (#855)

AUTHORS

@@ -44,6 +44,7 @@ Ori Livneh <ori.livneh@gmail.com>
 Paul Redmond <paul.redmond@gmail.com>
 Radoslav Yovchev <radoslav.tm@gmail.com>
 Roman Lebedev <lebedev.ri@gmail.com>
+Sayan Bhattacharjee <aero.sayan@gmail.com>
 Shuo Chen <chenshuo@chenshuo.com>
 Steinar H. Gunderson <sgunderson@bigfoot.com>
 Stripe, Inc.

CONTRIBUTORS

@@ -65,6 +65,7 @@ Raul Marin <rmrodriguez@cartodb.com>
 Ray Glover <ray.glover@uk.ibm.com>
 Robert Guo <robert.guo@mongodb.com>
 Roman Lebedev <lebedev.ri@gmail.com>
+Sayan Bhattacharjee <aero.sayan@gmail.com>
 Shuo Chen <chenshuo@chenshuo.com>
 Tobias Ulvgård <tobias.ulvgard@dirac.se>
 Tom Madams <tom.ej.madams@gmail.com> <tmadams@google.com>

README.md

@@ -422,6 +422,22 @@ BENCHMARK(BM_memcpy)->RangeMultiplier(2)->Range(8, 8<<10);
 ```
 Now arguments generated are [ 8, 16, 32, 64, 128, 256, 512, 1024, 2k, 4k, 8k ].
 
+The preceding code shows a method of defining a sparse range.  The following
+example shows a method of defining a dense range. It is then used to benchmark
+the performance of `std::vector` initialization for uniformly increasing sizes.
+
+```c++
+static void BM_DenseRange(benchmark::State& state) {
+  for(auto _ : state) {
+    std::vector<int> v(state.range(0), state.range(0));
+    benchmark::DoNotOptimize(v.data());
+    benchmark::ClobberMemory();
+  }
+}
+BENCHMARK(BM_DenseRange)->DenseRange(0, 1024, 128);
+```
+Now arguments generated are [ 0, 128, 256, 384, 512, 640, 768, 896, 1024 ].
+
 You might have a benchmark that depends on two or more inputs. For example, the
 following code defines a family of benchmarks for measuring the speed of set
 insertion.