Draw sin.x

sin(x)-x1.c

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

typedef struct {
  int x, y;
} P;

typedef struct {
  int w, h;
} B;

const float PI = 3.1415926;

const B box = {.w = 128, .h = 32 };

enum { NO = 0, YES = 1 };

int art(int x, int y, const int n) {

  P p = { .x = x, .y = 0 };
  int t = n;
  if (n < 1) {
    t = 1;
  }
  
  p.y = sin((double)p.x/(box.w * 1 / t) * PI) * box.h / 2 + box.h / 2;
  
  if (p.y == y) {
    return YES;
  }
  
  return NO;
}

void draw(const int n) {
  for (int j = 0; j < box.h; j++) {
    for (int i = 0; i < box.w; i++) {
      if (art(i, j, n)) {
        putchar('x');
      } else {
        if (j == box.h / 2) {
          putchar('-');
        } else {
          putchar(' ');
        }
      }
    }
    putchar('\n');
  }
}

int main(int argc, char *argv[])
{
  int step = 1;
  scanf("%d", &step);
  draw(step);
  
  return 0;
}

sin(x).c

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

typedef struct {
  int x, y;
} P;

typedef struct {
  int w, h;
} B;

const B box = {.w = 32, .h = 32 };

enum { NO = 0, YES = 1 };

int art(int x, int y) {

  P p = { .x = x, .y = 0 };
  
  p.y = sin((double)p.x/(box.w * 0.5) * 3.1415926) * box.h / 2 + box.h / 2;
  
  if (p.y == y) {
    return YES;
  }
  
  return NO;
}


int main(int argc, char *argv[])
{
  for (int j = 0; j < box.h; j++) {
    for (int i = 0; i < box.w; i++) {
      if (art(i, j)) {
        putchar('x');
      } else {
        putchar(' ');
      }
      
      if (j == box.h / 2) {
        putchar('-');
      }
      
    }
    putchar('\n');
  }
  return 0;
}

$ gcc sin(x)-x1.c
$ ./a.out
4