A velocity model for a simple DC motor

dc_motor_velocity_model.c

#include <stdio.h>

#define ITERATIONS 10

typedef struct
{
  double a;
  double b;
} motor_props_t;

double voltage(int *it)
{
  return 5;
}

double dc_motor(motor_props_t *motor_props, double (*vol)(int *), int *it)
{
  if (*it == 0)
  {
    return 0;
  }

  double mem = 0;

  for (unsigned int i = 0; i < *it; ++i)
  {
    mem = motor_props->a * mem + motor_props->b * vol(it);
  }

  return mem;
}

int main(void)
{
  motor_props_t motor_props;
  motor_props.a = 0.5;
  motor_props.b = 1;

  double results[ITERATIONS];

  for (unsigned int i = 0; i < ITERATIONS; ++i)
  {
    results[i] = dc_motor(&motor_props, voltage, &i);
  }

  for (unsigned int i = 0; i < ITERATIONS; ++i)
  {
    printf("%d: ", i);

    for (unsigned int j = 0; j < results[i]; ++j)
    {
      printf("—");
    }

    printf("\n");
  }

  return 0;
}