Thread: powers without .math?

I would write a function. http://www.cprogramming.com/tutorial/c/lesson4.html

I think a for loop and a if statement would be needed in the function.

Tim S.

1 = 1
3 = 1 * 3
9 = 1 * 3 * 3
27 = 1 * 3 * 3 * 3

I decided maybe the math was your issue.

Tim S.

Ignore what was previously here. Except for the thank yous

So I have now got my code to read:

Code:

#include <stdio.h>
#include <stdlib.h>


int main(void) {
	int x, n, answer1, first;
		x = 3;
		n = 10;
		first = 1;
		float answer2;
		int i;
		answer2 = 1.0;
		answer1 = 1;
		answer1 = x;
		for (i = 0; i < n; i++) {
		printf("%5d %d %1.9f\n", answer1, i, answer2);
			answer1 = answer1*x;
			answer2 = 1.00/answer1;
			}
	return EXIT_SUCCESS;
}

Which is basically what I want EXCEPT, I want the whole first column knocked down 1 (so it starts at 0 and ends at 19683) I am sure this is a REALLY simple fix, but I stuck myself...

101 decimal is 1100101 in binary, you can right shift it to get 50, 25, 12, 6, 3, 2, 1, 0. I don't think that's the answer though, I can think of any way to actually change the first number to 0 while maintaining everything else. The best I can think of is to add if/else logic into the for loop (you can either print a column of 0's before the 101, or print a column of 0's instead of the 101).

ummm... sorry but I'm really lost as to where binary came in here...

I feel confused haha

Basically I want these results:

Code:

           1  0  1.0
           3  1  0.333333343
           9  2  0.111111112
          27  3  0.037037037
          81  4  0.012345679
         243  5  0.004115226
         729  6  0.001371742
        2187  7  0.000457247
        6561  8  0.000152416
       19683  9  0.000050805

But I get this:

Code:

    3 0 1.000000000
    9 1 0.111111112
   27 2 0.037037037
   81 3 0.012345679
  243 4 0.004115226
  729 5 0.001371742
 2187 6 0.000457247
 6561 7 0.000152416
19683 8 0.000050805
59049 9 0.000016935

Code:

 answer1 = 1;answer1 = x;

You are beginning this number at 3 instead of 1. Think that should be it.


Sorry about the shifting thing, I thought you were trying to do it through bit shifting for some reason.

here is one problem:

Code:

		answer1 = 1;
		answer1 = x;

(edited)
Alpo already had it. I type too slow.

-

Originally Posted by Alpo

Code:

 answer1 = 1;answer1 = x;

You are beginning this number at 3 instead of 1. Think that should be it.


Sorry about the shifting thing, I thought you were trying to do it through bit shifting for some reason.

Wow thank you so much! That was a really simple fix.... I almost feel dumb xD

No worries! it was probably because my initial code that I posted had bit shifting in it for whatever reason

As for the i/answer1 thing, no I have that correct. I never really specified here what the other two columns were for as I had them figured out, but the three were 3^k, k, and 3^-k (or 1/3^k) so 1.00/answer1 was what I needed