Ruler58585

12-04-2011, 03:51 AM

Series given are the first four fractions of the series (1st, 2nd, 3rd or 4th). I convert each place to the original x value it was generated from, this assumes they will match and then tests to see if they do indeed match up the equations that I reversed to come up with the x's in each are as follows.

e^x = 1 + x + (x^2)/2 + x^3/6

cos(x) = 1 - (x^2)/2 + (x^4)/24 - (x^6)/720

sin(x) = x - (x^3)/6 + (x^5)/120 - (x^7)/5040

tan(x) = x + x^3 + (2x^5)/15 + (17x^7)/315

I plan on adding tanh(-1/x), Ln (1+x) and any others i can find eventually, but first things first why doesn't this work?

This is my second program and i'd like to learn any quicker/more effective ways to code, criticism (likely lots) is welcome.

//exponential series and log series

#include <stdio.h>

#include <iostream>

#include <math.h>

using namespace std;

static float x1 = 0.0;

static float x2 = 0.0;

static float x3 = 0.0;

static float x4 = 0.0;

static float r1 = 0.0;

static float r2 = 0.0;

static float r3 = 0.0;

static float r4 = 0.0;

int variablereset ()

{

r1 = x1;

r2 = x2;

r3 = x3;

r4 = x4;

}

int main()

{

cout << "1st" << endl;

cin >> x1 ;

cout << "2nd" << endl;

cin >> x2 ;

cout << "3rd" << endl;

cin >> x3 ;

cout << "4th" << endl;

cin >> x4 ;

cout << "Awnser is " ";

variablereset();

cout<< r1 << " " << r2 << " " << r3 << " " << r4;

r3 = r3 * 2.0;

r3 = (pow(r3, 1.0/2.0));

r4 = r4 * 6.0;

r4 = (pow(r4, 1.0/3.0));

if (r1 == 1.0 && r2 == r3 && r3 == r4)

{

cout << pow(2.71828183 , r2/1.0);

cout<< "e";

}

variablereset();

r2 = r2 * -6;

r2 = (pow(r2, 1.0/2.0));

r3 = r3 * 24;

r3 = (pow(r3, 1.0/4.0));

r4 = r4 * -120;

r4 = (pow(r4, 1.0/6.0));

if (r1 == 1 && r2 == r3 && r3 == r4)

{

cout << cos (r2);

cout<< "cos";

}

variablereset();

r2 = r2 * 6;

r2 =(pow(r2, 1.0/3.0));

r3 = r3 * 120;

r3 =(pow(r3, 1.0/4.0));

r4 = r4 * 5040;

r4 =(pow(r4, 1.0/6.0));

if (r1 == r2 && r2 == r3 && r3 == r4)

{

cout<< sin (r2);

cout<< "sin";

}

variablereset();

r2 =(pow(r2,1.0/3.0));

r3 = (r3*15)/2 ;

r3 =(pow(r3,1.0/5.0));

r4 = (r4 * 315)/17;

r4 =(pow(r4,1.0/7.0));

if (r1 == r2 && r2 == r3 && r3 == r4)

{

cout<< tan (r2);

cout<< "tan";

}

cout << " " << endl;

return 0;

}

I played with removing parts of code and testing using (1, 6, 18, 36) 1=1, 6=6, (18*2)^1/2=6, and (36*6)^1/3 i got the values 1,6,6,6 however when i check the 3rd term to the 4th term it comes false, the last "6" doesn't seem to be valid for some reason

I do realize this will not be 100% accurate I assume i'm given real fractional or decimal values and positive x values (though handling negatives as well would be nice)

Help appreciated!

e^x = 1 + x + (x^2)/2 + x^3/6

cos(x) = 1 - (x^2)/2 + (x^4)/24 - (x^6)/720

sin(x) = x - (x^3)/6 + (x^5)/120 - (x^7)/5040

tan(x) = x + x^3 + (2x^5)/15 + (17x^7)/315

I plan on adding tanh(-1/x), Ln (1+x) and any others i can find eventually, but first things first why doesn't this work?

This is my second program and i'd like to learn any quicker/more effective ways to code, criticism (likely lots) is welcome.

//exponential series and log series

#include <stdio.h>

#include <iostream>

#include <math.h>

using namespace std;

static float x1 = 0.0;

static float x2 = 0.0;

static float x3 = 0.0;

static float x4 = 0.0;

static float r1 = 0.0;

static float r2 = 0.0;

static float r3 = 0.0;

static float r4 = 0.0;

int variablereset ()

{

r1 = x1;

r2 = x2;

r3 = x3;

r4 = x4;

}

int main()

{

cout << "1st" << endl;

cin >> x1 ;

cout << "2nd" << endl;

cin >> x2 ;

cout << "3rd" << endl;

cin >> x3 ;

cout << "4th" << endl;

cin >> x4 ;

cout << "Awnser is " ";

variablereset();

cout<< r1 << " " << r2 << " " << r3 << " " << r4;

r3 = r3 * 2.0;

r3 = (pow(r3, 1.0/2.0));

r4 = r4 * 6.0;

r4 = (pow(r4, 1.0/3.0));

if (r1 == 1.0 && r2 == r3 && r3 == r4)

{

cout << pow(2.71828183 , r2/1.0);

cout<< "e";

}

variablereset();

r2 = r2 * -6;

r2 = (pow(r2, 1.0/2.0));

r3 = r3 * 24;

r3 = (pow(r3, 1.0/4.0));

r4 = r4 * -120;

r4 = (pow(r4, 1.0/6.0));

if (r1 == 1 && r2 == r3 && r3 == r4)

{

cout << cos (r2);

cout<< "cos";

}

variablereset();

r2 = r2 * 6;

r2 =(pow(r2, 1.0/3.0));

r3 = r3 * 120;

r3 =(pow(r3, 1.0/4.0));

r4 = r4 * 5040;

r4 =(pow(r4, 1.0/6.0));

if (r1 == r2 && r2 == r3 && r3 == r4)

{

cout<< sin (r2);

cout<< "sin";

}

variablereset();

r2 =(pow(r2,1.0/3.0));

r3 = (r3*15)/2 ;

r3 =(pow(r3,1.0/5.0));

r4 = (r4 * 315)/17;

r4 =(pow(r4,1.0/7.0));

if (r1 == r2 && r2 == r3 && r3 == r4)

{

cout<< tan (r2);

cout<< "tan";

}

cout << " " << endl;

return 0;

}

I played with removing parts of code and testing using (1, 6, 18, 36) 1=1, 6=6, (18*2)^1/2=6, and (36*6)^1/3 i got the values 1,6,6,6 however when i check the 3rd term to the 4th term it comes false, the last "6" doesn't seem to be valid for some reason

I do realize this will not be 100% accurate I assume i'm given real fractional or decimal values and positive x values (though handling negatives as well would be nice)

Help appreciated!