Seismic Code

/* determines the times of possible seismic events. */

#include <stdio.h>

#define FILENAME "seismic1.txt"

#define MAX_SIZE 1000

float THRESHOLD = 0;
int x = 0;

int main(void)

{

/* Declare variables and function prototypes. */
while(THRESHOLD <=2 1){
printf("Enter Threshold: \n");
scanf(" %f ", &THRESHOLD);
printf("Threshold: %f \n", THRESHOLD);
}
int k, npts, short_window, long_window;

double sensor[MAX_SIZE], time_incr, short_power,

long_power, ratio;

FILE *file_ptr;

double power_w(double *ptr,int n);

/* Read sensor data file. */

file_ptr = fopen(FILENAME,"r");

if (file_ptr == NULL)

printf("Error opening input file. \n");

else

{

fscanf(file_ptr,"%d %lf",&npts,&time_incr);

if (npts > MAX_SIZE)

printf("Data file too large for array. \n");

else

{

/* Read data into an array. */

for (k=0; k<=npts-1; k++)

fscanf(file_ptr,"%lf",&sensor[k]);

/* Read window sizes from the keyboard. */

printf("Enter number of points for short window: \n");

scanf("%d",&short_window);

printf("Enter number of points for long window: \n");

scanf("%d",&long_window);

/* Compute power ratios and search for events. */

for (k=long_window-1; k<=npts-1; k++)

{

short_power = power_w(&sensor[k],short_window);

long_power = power_w(&sensor[k],long_window);

ratio = short_power/long_power;

if (ratio > THRESHOLD){

printf("Possible event at %f seconds \n", time_incr*k);
x= x+1;
}
}
printf("Number of events: %i ", x);
/* Close file. */

fclose(file_ptr);

}

}

return 0;

}

/*????????????????????????????????????????????????????????????-*/

/* This function computes the average power in a specified */

/* window of a double array. */

double power_w(double *ptr, int n)

{

/* Declare and initialize variables. */

int k;

double xsquare=0;

/* Compute sum of values squared in the array x. */

for (k=0; k<=n-1; k++)

xsquare += *(ptr-k)*(*(ptr-k));

/* Return the average squared value. */

return xsquare/n;


}