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--- haas:spring2016:cprog:projects:pnc0 [2016/02/25 17:54] – [Check Results] wedge
+++ haas:spring2016:cprog:projects:pnc0 [2016/02/27 13:13] (current) – [Program] wedge
@@ Line 123: / Line 123: @@
   * [[https://lab46.g7n.org/~wedge/php/web.php?width=800&height=600&div=12&max=145&prime=1&factor=0&spiral=0|Visualization of Primes in a web of 12 divisions]]
   * [[https://en.wikipedia.org/wiki/Ulam_spiral|Ulam spiral]]
+  * [[https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes|Sieve of Eratosthenes]]
+Of particular note: the sieve algorithms take advantage of a increased storage space, where others (like brute force) are predominantly time-based. The sieve is also more detailed... even if you don't decide to implement a sieve, take a look and compare the algorithm to what you've done to see the differences in approaches.
 =====Program=====
 It is your task to write 3 separate prime number calculating programs:
-  - primebrute.c: for your brute force implementation
+  - **primebrute.c**: for your brute force implementation
-  - primesqrt.c: for your square root-optimization of the brute force
+  - **primesqrt.c**: for your square root-optimization of the brute force
-  - primeopt.c: for your optimized solution, be it basing off the existing ones, or taking a different approach
+  - **primeopt.c**: for your optimized solution, be it basing off the existing ones, or taking a different approach
 Your program should:
@@ Line 136: / Line 139: @@
     * these values should be positive integer values; you can make the assumption that the user will always do the right thing.
   * start your stopwatch (see **timing** section below):
-  * perform the correct algorithm against the input
+  * perform the algorithm against the value
   * if enabled, display the prime numbers found in the range
   * output the processing run-time to STDERR (do this always).
@@ Line 143: / Line 146: @@
     * the timing information will be displayed in accordance to code I will provide (in the **timing** section).
+====Other considerations====
+All your programs MUST perform the calculations to determine primality- you may not always be printing it out (depending on argv[2]), but work must be done to ensure the value is identified as a prime/composite value.
+For example:
+<code>
+if (show == 1)
+{
+	work to determine if it is prime
+	if prime
+		print number
+}
+</code>
+will actually skip the core processing, and you’ll see some amazing runtimes as a result. They may be amazing, but they’re not real, because you’re not actually doing anything.
+What you want instead:
+<code>
+work to determine if it is prime
+if (show == 1)
+{
+	if prime
+		print number
+}
+</code>
+there are many ways to express the above, through compound if statements and other arrangements, but notice how nothing is holding back “work to determine if it is prime”.
+That also isn’t to say you can’t avoid doing a work run if you’re able to determine its non-primality with a simple pretest (even value, factor of 3, etc.), but that’s actually considered more of the core “work”, so it is more than okay (and encouraged in the primeopt).
 =====Command-Line Arguments=====
 To automate our comparisons, we will be making use of command-line arguments in our programs. As we have yet to really get into arrays, I will provide you same code that you can use that will allow you to utilize them for the purposes of this project.

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