updated intro_lab instruction

intro_lab/README.md

@@ -94,7 +94,7 @@ Questions:
 - How many different ways are there to change the number of threads? Which one are those?
 - How can you make the output ordered from thread 0 to thread 4?
 
-## Exercise 2 - Creating Threads: calculate π in parallel using only pragma omp parallel
+## Exercise 2 - Creating Threads: calculate π in parallel using pragma omp parallel
 
 _Concepts: Parallel, default data environment, runtime library calls_
 
@@ -213,15 +213,15 @@ Questions:
 - What would happen if you hadn’t used critical or atomic a shared variable?
 - How does the execution time change varying the number of threads? Is it what
   you expected?
-- Do the two version of the codes differ in performance? If so, what do you
-  think it is the reason?
+- Do the two versions of the code differ in performance? If so, what do you
+  think is the reason?
 
 ## Exercise 4 - Calculate π with a loop and a reduction
 
 _Concepts: worksharing, parallel loop, schedule, reduction_
 
 Here we are going to implement a fourth parallel version of the pi.c / pi.f90
-code to calculate the value of π using omp for and reduction operations.
+code to calculate the value of π using ``omp for`` and ``reduction`` operations.
 
 Instructions: Create a new parallel versions of the pi.c / pi.f90 program using
 the parallel construct ``#pragma omp for`` and ``reduction`` operation. Run the new
@@ -231,7 +231,7 @@ the execution time for 1, 2, 4, 8, 16, 32 threads.
 
 Hints:
 
-To change the schedule, you can either change the environment variable with
+- To change the schedule, you can either change the environment variable with
 ``export OMP_SCHEDULE=type`` where ``type`` can be any of static, dynamic, guided or in
 the source code as ``omp parallel for schedule(type)``.
 
@@ -239,5 +239,5 @@ Questions:
 
 - What is the scheduling that provides the best performance? What is the reason for that?
 - What is the fastest parallel implementation of pi.c / pi.f90 program? What is
-  the reason for being the fastest? What would be an even faster implementation
+  the reason for it being the fastest? What would be an even faster implementation
   of pi.c / pi.f90 program?

intro_lab/hello.c

 #include <stdio.h>
+
 int main ()
 {
-  int ID = 0; // thread id
+    int thread_id = 0;
 
-  printf("Hello World from thread %d \n", ID);
+    printf("Hello World from thread %d \n", thread_id);
 }

intro_lab/pi.c

@@ -13,10 +13,13 @@ from the OpenMP runtime library
 History: Written by Tim Mattson, 11/99.
 
 */
+
 #include <stdio.h>
 #include <omp.h>
+
 static long num_steps = 100000000;
 double step;
+
 int main ()
 {
     int i;
@@ -25,7 +28,6 @@ int main ()
 
     step = 1.0/(double) num_steps;
 
-        	 
     start_time = omp_get_wtime();
 
     for (i=1;i<= num_steps; i++){
@@ -37,8 +39,3 @@ int main ()
     run_time = omp_get_wtime() - start_time;
     printf("\n pi with %ld steps is %lf in %lf seconds\n ",num_steps,pi,run_time);
 }
-
-
-
-
-