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

double atof();
double log();

main(argc, argv)
int argc;
char *argv[];
{
char tmp[200];
double pvalue =0;
double interest = 0;
double fvalue = 0;
double length = 0;

if ((argc == 2) && ((argv[1][0] == 'p') || (argv[1][0] == 'P')))
	{
	 fprintf(stdout,"Enter present value <$>.................... ");
	 fgets(tmp,100,stdin);
	 pvalue = atof(tmp);
	 fprintf(stdout,"Enter future value <$>..................... ");
	 fgets(tmp,100,stdin);
	 fvalue = atof(tmp);
	 fprintf(stdout,"Enter interest per compounding period...... ");
	 fgets(tmp,100,stdin);
	 interest = atof(tmp) / 100;
	 fprintf(stdout,"\n");
	}
else if ((argc == 2) && ((argv[1][0] == 'v') || (argv[1][0] == 'V')))
	{
	 fprintf(stdout,"cterm: Version 1.00 \n");
	 fprintf(stdout,"       Copyright 1987 by Michael Brochstein\n");
	 fprintf(stdout,"       All rights reserved.\n");
	}
else if (argc != 4) 
	{
	 fprintf(stderr,"Usage: cterm p \n");
	 fprintf(stderr,"       cterm v \n");
	 fprintf(stderr,"       cterm <present value> <future value> ");
	 fprintf(stderr,"<interest per compounding period>\n");
	}
else if (argc == 4)
	{
	 pvalue = atof(argv[1]);
	 fvalue = atof(argv[2]);
	 interest = atof(argv[3]) / 100;
	}

if ((argc == 4) 
	|| ((argc == 2) && ((argv[1][0] == 'p') || (argv[1][0] == 'P'))))
	{
	 length = log(fvalue/pvalue) / log(1 + interest);
	 fprintf(stdout,"It will take %.2f periods.\n",length);
	}
}