comments and more

bin.c

@@ -49,6 +49,7 @@ int main(int argc, char *argv[]){
 			int char_walker=1;
 			char current_char=current_arg[char_walker];
 			while(current_char != '\0'){
+				// TODO switch case
 				if(current_char == 'h')
 					usage(EXIT_SUCCESS, "");
 				else if(current_char == 'a'){

bin_dfs.c

 #include <inttypes.h> // uint64_t
 #include "bin_dfs.h"
 
-// private helper functions
-long double cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error);
-long double one_minus_cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error);
-long double pmf_helper(uint64_t k, uint64_t n, long double p);
-
-
-// declarations of public driver functions
-long double pmf(uint64_t k, uint64_t n, long double p){
+// TODO store even numbers as private args to helper functions and bitshift at the end
+// probably could store a pointer to our even numbers...?
+long double bin_pmf(uint64_t k, uint64_t n, long double p){
 	if(k > n)
 		return 0.0; // the function is being used improperly so return 0.0.
 	if(2*k>n && p > 0.5)
@@ -16,44 +11,43 @@ long double pmf(uint64_t k, uint64_t n, long double p){
 	return pmf_helper(k, n, p);
 }
 
-long double cdf(uint64_t k, uint64_t n, long double p){
-	if(2*k>n)
-		return 1-one_minus_cdf_helper(k+1, n, p, 0.0, 0.0);
-	return cdf_helper(k, n, p, 0.0, 0.0);
-}
-
-
-// Can't do tail recursion here because the intermediate products can get
-// far larger than LDBL_MAX
-long double pmf_helper(uint64_t k, uint64_t n, long double p){
+long double bin_pmf_helper(uint64_t k, uint64_t n, long double p){
+	// Can't do tail recursion here because the intermediate products can get
+	// far larger than LDBL_MAX
 	// work through our k's then work through our n's.
 	if(n == 0)
 		return 1.0;
 	if(k == 0)
 		return (1-p)*pmf_helper(0, n-1, p);
-	return n*p*pmf_helper(k-1, n-1, p)/k;
+	return n*p*bin_pmf_helper(k-1, n-1, p)/k;
+}
+
+long double cdf(uint64_t k, uint64_t n, long double p){
+	if(2*k>n)
+		return 1-one_minus_cdf_helper(k+1, n, p, 0.0, 0.0);
+	return cdf_helper(k, n, p, 0.0, 0.0);
 }
 
 // accumulate a sum and error using tail recursion. Call with sum = error = 0.0
-long double cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error){
+long double bin_cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error){
 	// sum until k == 0
 	if(k == 0)
-		return sum + pmf(0, n, p) + error; // add error back to sum to get 
+		return sum + pmf(0, n, p) + error; // add error back to sum to get a more accurate answer
 
 	// perform a compensated addition on sum
 	long double temp = pmf(k, n, p);
 	long double next = sum + temp;
-	return cdf_helper(k-1, n, p, next, error+((sum-next)+temp));
+	return bin_cdf_helper(k-1, n, p, next, error+((sum-next)+temp));
 }
 
 // calculates 1-cdf(k). Can result in fewer steps to find a solution to 1-cdf(k) if 2*k>n.
-long double one_minus_cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error){
+long double bin_one_minus_cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error){
 	// sum until k == n
 	if(k > n)
-		return sum + error; // add error back to sum to get 
+		return sum + error; // add error back to sum to get a more accurate answer
 
 	// perform a compensated addition on sum
 	long double temp = pmf(k, n, p);
 	long double next = sum + temp;
-	return one_minus_cdf_helper(k+1, n, p, next, error+((sum-next)+temp));
+	return bin_one_minus_cdf_helper(k+1, n, p, next, error+((sum-next)+temp));
 }

bin_dfs.h

@@ -12,7 +12,7 @@
  * Returns:
  * 	 (n_choose_k)*(p^k)*((1-p)^(n-k)) if k<=n, 0 otherwise
  */
-long double pmf(uint64_t k, uint64_t n, long double p);
+long double bin_pmf(uint64_t k, uint64_t n, long double p);
 
 
 /*
@@ -24,7 +24,12 @@ long double pmf(uint64_t k, uint64_t n, long double p);
  * 	 P(X<=k) where X~bin(n, p)
  * 	 ie, \sum_{j=0}^k pmf(j, n, p)
  */
-long double cdf(uint64_t k, uint64_t n, long double p);
+long double bin_cdf(uint64_t k, uint64_t n, long double p);
+
+// private helper functions called by pmf and cdf
+long double bin_cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error);
+long double bin_one_minus_cdf_helper(uint64_t k, uint64_t n, long double p, long double sum, long double error);
+long double bin_pmf_helper(uint64_t k, uint64_t n, long double p);
 
 #endif // DIST_FUNCT_H