Thread: exponential numbers

Hi, i am trying to write a program that produces an out put that looks like the fallowing, using "printf()" and "scanf()"

Code:

X                     X^2                  X^3
2.0e+000       4.00e+000       8.00e+000
3.0e+000       9.00e+000       2.70e+001
4.0e+000       1.60e+001       6.40e+001
5.0e+000       2.50e+001       1.25e+002
6.0e+000       3.60e+001       2.16e+002
7.0e+000       4.90e+001       3.43e+002
8.0e+000       6.40e+001       5.12e+002
9.0e+000       8.10e+001       7.29e+002

but the output that i am getting is nothing like it...

Code:

X                                 X^2                                X^3
2.121996e-314          4.940656e-324              1.#QNAN0e+000
8.487983e-314          3.952525e-323              1.#QNAN0e+000
1.909796e-313          1.333977e-322              1.#QNAN0e+000
3.395193e-313          3.162020e-322              1.#QNAN0e+000
5.304989e-313          6.175821e-322              1.#QNAN0e+000
7.639185e-313          1.067182e-321              1.#QNAN0e+000
1.039778e-312          1.694645e-321              1.#QNAN0e+000
1.358077e-312          2.529616e-321              1.#QNAN0e+000
1.718817e-312          3.601739e-321              1.#QNAN0e+000

my best guess is that the data i am trying to produce are exponential numbers (& the second column is the first one squared, and the third column is cubed) so i used the fallowing code... but i cant understand why it isn't working... please help

Code:

#include "stdafx.h"

int _tmain(int argc, _TCHAR* argv[]) {
  // Declare varaibles
	float tbStart, tbEnd;
	
  // Prompt for input
	// First Number
	printf("Please enter the first number for the table: ");
	scanf("%e", &tbStart);
	
	// Last Number
	printf("Please enter the last number for the table: ");
	scanf("%e", &tbEnd);
	
  // print table header
	printf("---------------------------------------------------------\n");
	printf("Table of infomation\n\n");
	printf("---------------------------------------------------------\n");
	
  // print table information
	printf("X                       X^2                     X^3\n");
	for (int i=tbStart; i<=tbEnd; i++) {
		int sqr = i*i; int cub = i*i*i;
		printf("%e\t\t%e\t\t%e\n",i,sqr,cub);
	}
	
  // print table footer
	printf("---------------------------------------------------------\n");
	scanf("%f",&tbEnd);
  // end of program
	return 0;
}

Originally Posted by swoopy

> int sqr = i*i; int cub = i*i*i;
> printf("%e\t\t%e\t\t%e\n",i,sqr,cub);
If you're going to print them out as floating point numbers, you might as well declare them as such (ie double).

Code:

		double sqr = i*i; double cub = i*i*i;
		printf("%e\t\t%e\t\t%e\n",(double) i,sqr,cub);

And depending on how big i gets, you may need to cast i in the calculations.

Code:

		double sqr = static_cast<double>(i)*i; double cub = static_cast<double>(i)*i*i;
		printf("%e\t\t%e\t\t%e\n",(double) i,sqr,cub);

Thanks alot for that, that works... but im not to sure what you are doing with the

Code:

static_cast<double>

ah cool, i get ya... thanks