title: Makefile for two compilers and different optimization techniques
body: <p>I have been trying to compile a single c program with two different compilers icc and gcc with different optimization techniques using this code. </p>
  
  <p>I tried using the following code in the Makefile. </p>
  
  <pre><code> output: prog3.o
      gcc prog3.o -o2 output
      gcc prog3.o -o3 output
      icc prog3.o -o2 output
   prog3.o: prog3.c
      gcc -c prog3.c
      gcc -c prog3.c
      icc -c prog3.c
  
   clean:
      rm *.o output
  </code></pre>
  
  <p>I got an output by executing the cmd, ./output</p>
  
  <p>i got output for one round of execution only. 
  for example, : </p>
  
  <pre><code> ./output 
  Total time taken by CPU for Matrix addition looping over row: 1.210000
  Total time taken by CPU for Matrix addition looping over column: 6.480000
  </code></pre>
  
  <p>Is it possible to have a single makefile that compiles both icc and gcc with different optimization techniques. I read online on many methods to create makefiles for gcc &amp; g++ or for multiple c prog.s but not my problem. </p>