Simple SIn Curve

[akinidu]

I just move from Matlab to C ;;;;;

I am trying to plot a Simple sin curve in C

 
 
#include <math.h>
#include <stdio.h>
 
#define PI 3.1415926535897932384626433832795l
 
int main()
{
  const float dt = .001;
  int i, n ;
  float  t,t1, y;
  t=0.0;
  n=20;
  printf(" i             t                   y \n");
  printf("------------------------------------ \n");
  for (i = 0; i <= n; i++)
  {
     t1=i*dt;
     y = sin(2*PI*t1);
     printf("%d %5e %2e \n", i, t1, y);
  }
  return 0;
}
 

I have few questions !

1. How i can get out put in terms of dat file ! I want to plot it in matlab later
2. In Matlab, when i run the same algorithmi get negative amplitudes also but here i am getting all positive ! This means my code is wrong some where
3. Also if i want to take random values of t1 instead of uniform ! suppose i want to chuck of 10% from this what should i do


Thanks

[akinidu]

Oh its fine i corrected this code but still i am not able to figure it out how can i chop of 30% of values from this curve randomly...............i wabt to use rand not srand as i am looking for chopping 5% fst then 10%..slowly slowly 50%

[weaknessforcats]

I don't know if this is important to you but a float contains only 6 significant digits. A double has only 15.