diff --git a/machine_learning/adaline_learning.c b/machine_learning/adaline_learning.c
index 3bac6823..ecef67b1 100644
--- a/machine_learning/adaline_learning.c
+++ b/machine_learning/adaline_learning.c
@@ -3,6 +3,8 @@
  * \brief [Adaptive Linear Neuron
  * (ADALINE)](https://en.wikipedia.org/wiki/ADALINE) implementation
  *
+ * \author [Krishna Vedala](https://github.com/kvedala)
+ *
  * <img
  * src="https://upload.wikimedia.org/wikipedia/commons/b/be/Adaline_flow_chart.gif"
  * width="200px">
diff --git a/machine_learning/kohonen_som_trace.c b/machine_learning/kohonen_som_trace.c
index ec894c44..4c313f77 100644
--- a/machine_learning/kohonen_som_trace.c
+++ b/machine_learning/kohonen_som_trace.c
@@ -3,6 +3,8 @@
  * \brief [Kohonen self organizing
  * map](https://en.wikipedia.org/wiki/Self-organizing_map) (data tracing)
  *
+ * \author [Krishna Vedala](https://github.com/kvedala)
+ *
  * This example implements a powerful self organizing map algorithm.
  * The algorithm creates a connected network of weights that closely
  * follows the given data points. This this creates a chain of nodes that
diff --git a/misc/collatz.c b/misc/collatz.c
index a99140ea..0ba7a0da 100644
--- a/misc/collatz.c
+++ b/misc/collatz.c
@@ -1,11 +1,18 @@
-/*
-collatz conjecture: a series for a number n in which if n even then the next
-number is n/2 ,but if n is odd then the next number is 3n+1. this series
-continues till it reaches 1*/
+/**
+ * \file
+ *
+ * \brief Implementation of [Collatz'
+ * conjecture](https://en.wikipedia.org/wiki/Collatz_conjecture)
+ *
+ * Collatz conjecture: a series for a number \f$n\f$ in which if \f$n\f$ even
+ * then the next number is \f$\frac{n}{2}\f$ ,but if n is odd then the next
+ * number is \f$3n+1\f$. This series continues till \f$n\f$ reaches 1
+ */
 
 #include <stdio.h>
 #include <stdlib.h>
 
+/** Main function */
 int main(int argc, char *argv[])
 {
     unsigned long long n, curr_no, num_steps = 0;
diff --git a/misc/factorial_large_number.c b/misc/factorial_large_number.c
index 2a77ddc2..9720d709 100644
--- a/misc/factorial_large_number.c
+++ b/misc/factorial_large_number.c
@@ -2,6 +2,7 @@
  * @file
  * \brief Compute factorial of arbitrarily large numbers by
  * storing individual digits in a byte.
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/misc/fibonacci_fast.c b/misc/fibonacci_fast.c
index 653ecfd4..e12a3b98 100644
--- a/misc/fibonacci_fast.c
+++ b/misc/fibonacci_fast.c
@@ -1,6 +1,6 @@
 /**
     @file
-    @author Krishna Vedala
+    @author [Krishna Vedala](https://github.com/kvedala)
     @date 2 October, 2019
     @brief Compute \f$m^{mth}\f$ Fibonacci number using the formulae:
     \f{eqnarray*}{
diff --git a/numerical_methods/durand_kerner_roots.c b/numerical_methods/durand_kerner_roots.c
index 443b8610..440fad1c 100644
--- a/numerical_methods/durand_kerner_roots.c
+++ b/numerical_methods/durand_kerner_roots.c
@@ -4,6 +4,8 @@
  * [Durand Kerner
  * algorithm](https://en.wikipedia.org/wiki/Durand%E2%80%93Kerner_method)
  *
+ * \author [Krishna Vedala](https://github.com/kvedala)
+ *
  * Test the algorithm online:
  * https://gist.github.com/kvedala/27f1b0b6502af935f6917673ec43bcd7
  *
@@ -249,4 +251,4 @@ end:
     free(s0);
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/numerical_methods/newton_raphson_root.c b/numerical_methods/newton_raphson_root.c
index e699b80b..7f071db9 100644
--- a/numerical_methods/newton_raphson_root.c
+++ b/numerical_methods/newton_raphson_root.c
@@ -2,6 +2,8 @@
  * @file
  * \brief Find approximate solution for \f$f(x) = 0\f$ using
  * Newton-Raphson interpolation algorithm.
+ *
+ * \author [Krishna Vedala](https://github.com/kvedala)
  **/
 
 #include <complex.h> /* requires minimum of C99 */
@@ -71,4 +73,4 @@ int main(int argc, char **argv)
            c >= 0 ? '+' : '-', c >= 0 ? c : -c, delta);
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/numerical_methods/qr_decompose.h b/numerical_methods/qr_decompose.h
index 4404b0b1..73513a39 100644
--- a/numerical_methods/qr_decompose.h
+++ b/numerical_methods/qr_decompose.h
@@ -1,9 +1,9 @@
 /**
  * @file
- *
  * \brief Library functions to compute [QR
  * decomposition](https://en.wikipedia.org/wiki/QR_decomposition) of a given
  * matrix.
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 
 #ifndef QR_DECOMPOSE_H
diff --git a/numerical_methods/qr_decomposition.c b/numerical_methods/qr_decomposition.c
index c758aaa0..f953b96b 100644
--- a/numerical_methods/qr_decomposition.c
+++ b/numerical_methods/qr_decomposition.c
@@ -3,6 +3,7 @@
  * \brief Program to compute the [QR
  * decomposition](https://en.wikipedia.org/wiki/QR_decomposition) of a given
  * matrix.
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 
 #include "qr_decompose.h"
@@ -76,4 +77,4 @@ int main(void)
     free(R);
     free(Q);
     return 0;
-}
\ No newline at end of file
+}
diff --git a/numerical_methods/qr_eigen_values.c b/numerical_methods/qr_eigen_values.c
index cfbb961c..5028b848 100644
--- a/numerical_methods/qr_eigen_values.c
+++ b/numerical_methods/qr_eigen_values.c
@@ -3,6 +3,7 @@
  * \brief Compute real eigen values and eigen vectors of a symmetric matrix
  * using [QR decomposition](https://en.wikipedia.org/wiki/QR_decomposition)
  * method.
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include "qr_decompose.h"
 #include <math.h>
@@ -170,4 +171,4 @@ int main(int argc, char **argv)
     free(Q);
     free(eigen_vals);
     return 0;
-}
\ No newline at end of file
+}
diff --git a/numerical_methods/realtime_stats.c b/numerical_methods/realtime_stats.c
index d2bac7a2..83064821 100644
--- a/numerical_methods/realtime_stats.c
+++ b/numerical_methods/realtime_stats.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief Compute statistics for data entered in rreal-time
+ * \author [Krishna Vedala](https://github.com/kvedala)
  *
  * This algorithm is really beneficial to compute statistics on data read in
  * realtime. For example, devices reading biometrics data. The algorithm is
diff --git a/project_euler/problem_10/sol1.c b/project_euler/problem_10/sol1.c
index 8e6976a2..560582bc 100644
--- a/project_euler/problem_10/sol1.c
+++ b/project_euler/problem_10/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 10](https://projecteuler.net/problem=10) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <math.h>
 #include <stdio.h>
diff --git a/project_euler/problem_10/sol2.c b/project_euler/problem_10/sol2.c
index 6926ae06..6c0cda64 100644
--- a/project_euler/problem_10/sol2.c
+++ b/project_euler/problem_10/sol2.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 10](https://projecteuler.net/problem=10) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <math.h>
 #include <stdio.h>
@@ -52,4 +53,4 @@ int main(int argc, char *argv[])
     printf("%ld: %lld\n", n, sum);
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/project_euler/problem_12/sol1.c b/project_euler/problem_12/sol1.c
index 46c0162b..d00814ac 100644
--- a/project_euler/problem_12/sol1.c
+++ b/project_euler/problem_12/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 12](https://projecteuler.net/problem=12) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <math.h>
 #include <stdio.h>
diff --git a/project_euler/problem_13/sol1.c b/project_euler/problem_13/sol1.c
index 2ee588c1..c1d05327 100644
--- a/project_euler/problem_13/sol1.c
+++ b/project_euler/problem_13/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 13](https://projecteuler.net/problem=13) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdint.h>
 #include <stdio.h>
diff --git a/project_euler/problem_14/sol1.c b/project_euler/problem_14/sol1.c
index 3190aabd..cfb2422f 100644
--- a/project_euler/problem_14/sol1.c
+++ b/project_euler/problem_14/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 14](https://projecteuler.net/problem=14) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  *
  * Since the computational values for each iteration step are independent,
  * we can compute them in parallel. However, the maximum values should be
diff --git a/project_euler/problem_15/sol1.c b/project_euler/problem_15/sol1.c
index 249fc124..c0dd1c79 100644
--- a/project_euler/problem_15/sol1.c
+++ b/project_euler/problem_15/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 15](https://projecteuler.net/problem=15) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdint.h>
 #include <stdio.h>
diff --git a/project_euler/problem_16/sol1.c b/project_euler/problem_16/sol1.c
index 91a38fbe..68a12cac 100644
--- a/project_euler/problem_16/sol1.c
+++ b/project_euler/problem_16/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 16](https://projecteuler.net/problem=16) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <math.h>
 #include <stdint.h>
diff --git a/project_euler/problem_19/sol1.c b/project_euler/problem_19/sol1.c
index fee6ebd7..4e91ee25 100644
--- a/project_euler/problem_19/sol1.c
+++ b/project_euler/problem_19/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 19](https://projecteuler.net/problem=19) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 
diff --git a/project_euler/problem_20/sol1.c b/project_euler/problem_20/sol1.c
index 9cd4cb79..1c6e9e1f 100644
--- a/project_euler/problem_20/sol1.c
+++ b/project_euler/problem_20/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 20](https://projecteuler.net/problem=20) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  *
  * Implementation uses a custom `big_int` structure that can store arbitrarilty
  * large integer numbers.
diff --git a/project_euler/problem_21/sol1.c b/project_euler/problem_21/sol1.c
index 90521fdc..d5b77145 100644
--- a/project_euler/problem_21/sol1.c
+++ b/project_euler/problem_21/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 21](https://projecteuler.net/problem=21) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/project_euler/problem_22/sol1.c b/project_euler/problem_22/sol1.c
index 6a8e7a42..bd8aee8d 100644
--- a/project_euler/problem_22/sol1.c
+++ b/project_euler/problem_22/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 22](https://projecteuler.net/problem=22) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/project_euler/problem_23/sol1.c b/project_euler/problem_23/sol1.c
index f88882c0..308b0362 100644
--- a/project_euler/problem_23/sol1.c
+++ b/project_euler/problem_23/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 23](https://projecteuler.net/problem=23) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/project_euler/problem_23/sol2.c b/project_euler/problem_23/sol2.c
index 44c00aec..6041d0a0 100644
--- a/project_euler/problem_23/sol2.c
+++ b/project_euler/problem_23/sol2.c
@@ -2,6 +2,7 @@
  * \file
  * \brief [Problem 23](https://projecteuler.net/problem=23) solution -
  * optimization using look-up array
+ * \author [Krishna Vedala](https://github.com/kvedala)
  *
  * Optimization applied - compute & store abundant numbers once
  * into a look-up array.
diff --git a/project_euler/problem_25/sol1.c b/project_euler/problem_25/sol1.c
index 44a33d9d..e5bef0bc 100644
--- a/project_euler/problem_25/sol1.c
+++ b/project_euler/problem_25/sol1.c
@@ -2,6 +2,7 @@
  * \file
  * \brief [Problem 25](https://projecteuler.net/problem=25) solution implemented
  * using arbitrarily large numbers represented as arrays
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdint.h>
 #include <stdio.h>
diff --git a/project_euler/problem_26/sol1.c b/project_euler/problem_26/sol1.c
index 6ddc1a80..b5359ed2 100644
--- a/project_euler/problem_26/sol1.c
+++ b/project_euler/problem_26/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 26](https://projecteuler.net/problem=26) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/project_euler/problem_401/sol1.c b/project_euler/problem_401/sol1.c
index 43eee4f0..ed260b32 100644
--- a/project_euler/problem_401/sol1.c
+++ b/project_euler/problem_401/sol1.c
@@ -1,8 +1,8 @@
 /**
  * \file
- * \brief [Problem 401](https://projecteuler.net/problem=401) solution
- *
+ * \brief [Problem 401](https://projecteuler.net/problem=401) solution -
  * Sum of squares of divisors
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdint.h>
 #include <stdio.h>
@@ -144,4 +144,4 @@ int main(int argc, char **argv)
     printf("Time taken: %.4gms\n", dtime * 1e3 / CLOCKS_PER_SEC);
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/project_euler/problem_8/sol1.c b/project_euler/problem_8/sol1.c
index 4b18a60a..01259489 100644
--- a/project_euler/problem_8/sol1.c
+++ b/project_euler/problem_8/sol1.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 8](https://projecteuler.net/problem=8) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/project_euler/problem_8/sol2.c b/project_euler/problem_8/sol2.c
index fda6ab0c..46569119 100644
--- a/project_euler/problem_8/sol2.c
+++ b/project_euler/problem_8/sol2.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 8](https://projecteuler.net/problem=8) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/project_euler/problem_9/sol1.c b/project_euler/problem_9/sol1.c
index 6a0a64b8..cba1a89a 100644
--- a/project_euler/problem_9/sol1.c
+++ b/project_euler/problem_9/sol1.c
@@ -2,6 +2,7 @@
  * \file
  * \brief [Problem 9](https://projecteuler.net/problem=9) solution - A naive
  * implementation
+ * \author [Krishna Vedala](https://github.com/kvedala)
  */
 #include <stdio.h>
 
@@ -22,4 +23,4 @@ int main(void)
             }
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/project_euler/problem_9/sol2.c b/project_euler/problem_9/sol2.c
index 69153b3e..4afe69d5 100644
--- a/project_euler/problem_9/sol2.c
+++ b/project_euler/problem_9/sol2.c
@@ -1,6 +1,7 @@
 /**
  * \file
  * \brief [Problem 9](https://projecteuler.net/problem=9) solution
+ * \author [Krishna Vedala](https://github.com/kvedala)
  *
  Problem Statement:
     A Pythagorean triplet is a set of three natural numbers, \f$a < b < c\f$,
diff --git a/sorting/shell_sort2.c b/sorting/shell_sort2.c
index 7802edf1..c6ae4851 100644
--- a/sorting/shell_sort2.c
+++ b/sorting/shell_sort2.c
@@ -1,20 +1,25 @@
+/**
+ * \file
+ * \brief [Shell sort algorithm](https://en.wikipedia.org/wiki/Shell_sort)
+ * implementation.
+ * \author [Krishna Vedala](https://github.com/kvedala)
+ */
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
 
-#define ELEMENT_NR 20000
 #define ARRAY_LEN(x) (sizeof(x) / sizeof((x)[0]))
 
-void show_data(int arr[], int len)
+/** Helper function to print array values */
+void show_data(int *arr, long len)
 {
-    int i;
-
-    for (i = 0; i < len; i++)
+    for (long i = 0; i < len; i++)
         printf("%3d ", arr[i]);
     printf("\n");
 }
 
-void swap(int *a, int *b)
+/** Function to swap values of two integers */
+inline void swap(int *a, int *b)
 {
     int tmp;
 
@@ -26,17 +31,17 @@ void swap(int *a, int *b)
 /**
  * Optimized algorithm - takes half the time as other
  **/
-void shell_sort(int array[], int LEN)
+void shell_sort(int *array, long LEN)
 {
     const int gaps[] = {701, 301, 132, 57, 23, 10, 4, 1};
     const int gap_len = 8;
-    int i, j, g;
+    long i, j, g;
 
     for (g = 0; g < gap_len; g++)
-    {
+    { // for each gap
         int gap = gaps[g];
         for (i = gap; i < LEN; i++)
-        {
+        { // from gap position to the end
             int tmp = array[i];
 
             for (j = i; j >= gap && (array[j - gap] - tmp) > 0; j -= gap)
@@ -50,27 +55,32 @@ void shell_sort(int array[], int LEN)
 #endif
 }
 
+/** Main function */
 int main(int argc, char *argv[])
 {
     int i;
-    int array[ELEMENT_NR];
-    int range = 500;
-    int size;
+    long size = 500;
+    if (argc == 2)
+        size = atol(argv[1]);
+    else if (argc > 2)
+        fprintf(stderr, "Usage: ./shell_sort [number of values]\n");
+
+    int *array = (int *)malloc(size * sizeof(int));
+    int range = 500; // range of array values
     double time_spent;
 
-    srand(time(NULL));
-    for (i = 0; i < ELEMENT_NR; i++)
+    srand(time(NULL)); // initialize random number generator
+    for (i = 0; i < size; i++)
+        // fill array with random integers
         array[i] = rand() % range + 1;
 
-    size = ARRAY_LEN(array);
-
-    show_data(array, size);
-    clock_t t1 = clock();
-    shell_sort(array, size);
-    clock_t t2 = clock();
+    show_data(array, size);  // show array before sorting
+    clock_t t1 = clock();    // start timer
+    shell_sort(array, size); // sort the array
+    clock_t t2 = clock();    // end timer
 
     printf("Data Sorted\n");
-    show_data(array, size);
+    show_data(array, size); // display array after sorting
 
     printf("Time spent sorting: %.4g s\n", (t2 - t1) / CLOCKS_PER_SEC);