Task: Fivenum

C: #include <stdio.h>
#include <stdlib.h>

double median(double *x, int start, int end_inclusive) {
    int size = end_inclusive - start + 1;
    if (size <= 0) {
        printf("Array slice cannot be empty\n");
        exit(1);
    }
    int m = start + size / 2;
    if (size % 2) return x[m];
    return (x[m - 1] + x[m]) / 2.0;
}

int compare (const void *a, const void *b) {
    double aa = *(double*)a; 
    double bb = *(double*)b;
    if (aa > bb) return 1;
    if (aa < bb) return -1;
    return 0;
}

int fivenum(double *x, double *result, int x_len) {
    int i, m, lower_end;
    for (i = 0; i < x_len; i++) {
        if (x[i] != x[i]) {
           printf("Unable to deal with arrays containing NaN\n\n");
           return 1;
        }
    } 
    qsort(x, x_len, sizeof(double), compare);
    result[0] = x[0];
    result[2] = median(x, 0, x_len - 1);
    result[4] = x[x_len - 1];
    m = x_len / 2;
    lower_end = (x_len % 2) ? m : m - 1;
    result[1] = median(x, 0, lower_end);
    result[3] = median(x, m, x_len - 1);
    return 0;
}

int show(double *result, int places) {
    int i;
    char f[7];
    sprintf(f, "%%.%dlf", places);
    printf("[");
    for (i = 0; i < 5; i++) {     
        printf(f, result[i]);
        if (i < 4) printf(", ");
    }
    printf("]\n\n");
}

int main() {
    double result[5];

    double x1[11] = {15.0, 6.0, 42.0, 41.0, 7.0, 36.0, 49.0, 40.0, 39.0, 47.0, 43.0};
    if (!fivenum(x1, result, 11)) show(result, 1);

    double x2[6] = {36.0, 40.0, 7.0, 39.0, 41.0, 15.0};
    if (!fivenum(x2, result, 6)) show(result, 1);

    double x3[20] = {
         0.14082834,  0.09748790,  1.73131507,  0.87636009, -1.95059594,  0.73438555,
        -0.03035726,  1.46675970, -0.74621349, -0.72588772,  0.63905160,  0.61501527,
        -0.98983780, -1.00447874, -0.62759469,  0.66206163,  1.04312009, -0.10305385,
         0.75775634,  0.32566578
    };
    if (!fivenum(x3, result, 20)) show(result, 9);

    return 0;
}











Ada: with Ada.Text_IO; use Ada.Text_IO;
with Ada.Containers.Generic_Array_Sort;

procedure Main is
   package Real_Io is new Float_IO (Long_Float);
   use Real_Io;

   type Data_Array is array (Natural range <>) of Long_Float;
   subtype Five_Num_Type is Data_Array (0 .. 4);

   procedure Sort is new Ada.Containers.Generic_Array_Sort
     (Index_Type => Natural, Element_Type => Long_Float,
      Array_Type => Data_Array);

   function Median (X : Data_Array) return Long_Float with
      Pre => X'Length > 0;

   function Median (X : Data_Array) return Long_Float is
      M : constant Natural := X'First + X'Last / 2;
   begin
      if X'Length rem 2 = 1 then
         return X (M);
      else
         return (X (M - 1) + X (M)) / 2.0;
      end if;
   end Median;

   procedure fivenum (X : Data_Array; Result : out Five_Num_Type) is
      Temp      : Data_Array := X;
      m         : Natural    := X'Length / 2;
      Lower_end : Natural    := (if X'Length rem 2 = 0 then m - 1 else m);
   begin
      Sort (Temp);
      Result (0) := Temp (Temp'First);
      Result (2) := Median (Temp);
      Result (4) := Temp (Temp'Last);
      Result (1) := Median (Temp (1 .. Lower_end));
      Result (3) := Median (Temp (m .. Temp'Last));
   end fivenum;

   procedure print (Result : Five_Num_Type; Aft : Natural) is
   begin
      Put ("[");
      for I in Result'Range loop
         Put (Item => Result (I), Fore => 1, Aft => Aft, Exp => 0);
         if I < Result'Last then
            Put (", ");
         else
            Put_Line ("]");
         end if;
      end loop;
      New_Line;
   end print;

   X1 : Data_Array :=
     (15.0, 6.0, 42.0, 41.0, 7.0, 36.0, 49.0, 40.0, 39.0, 47.0, 43.0);
   X2 : Data_Array := (36.0, 40.0, 7.0, 39.0, 41.0, 15.0);
   X3 : Data_Array :=
     (0.140_828_34, 0.097_487_90, 1.731_315_07, 0.876_360_09, -1.950_595_94,
      0.734_385_55, -0.030_357_26, 1.466_759_70, -0.746_213_49, -0.725_887_72,
      0.639_051_60, 0.615_015_27, -0.989_837_80, -1.004_478_74, -0.627_594_69,
      0.662_061_63, 1.043_120_09, -0.103_053_85, 0.757_756_34, 0.325_665_78);
   Result : Five_Num_Type;
begin
   fivenum (X1, Result);
   print (Result, 1);
   fivenum (X2, Result);
   print (Result, 1);
   fivenum (X3, Result);
   print (Result, 9);
end Main;