Write a program to compute the value of sin(x) using built-in function and using user _define function

Asked Nov 13 '20 at 19:55

Active Nov 14 '20 at 14:20

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Q: Write a program to compute the value of sin(x) using built-in function and using user-defined function (your own function), then print out the result. The values of x=30,45,60,90,180. Write the output of the built-in function and user-defined function.

when I answered the Q I tried all angels and the answer true but when I entered 180 and 360 consul gave me :

enter any degree
180
sin (x) = -8.74228e-08

but the answer should be 0

the code :

#include <iostream>
#include <math .h>
using namespace s td;
float F1(float x) {
  x = (x*3.14159265359) / 180;
  x = sin(x);
  return x;
}

int main() {
  float y;
  cout << "enter any degree"<<end l;
  cin >> y;
  y = F1(y);
  cout << "sin (x) = " << y;
  return 0;
}

edited Nov 14 '20 at 14:20

ocrdu

2,172
6
15
22

asked Nov 13 '20 at 19:55

omar haj

1

because sin(-0.0000000874228) is that – user253751 Nov 13 '20 at 19:56
Where did all those spaces in the identifiers come from? `c in`, `c out` etc? – cigien Nov 13 '20 at 19:56
1

Because 3.14159265359 ≠ π, we would not expect the result to be 0. – njuffa Nov 13 '20 at 20:03
It is very nearly 0, though. I would round it to zero, I really would. Try with 3,1415926535897932384626433832795 , and see if it gets any better. – ocrdu Nov 13 '20 at 20:06
So what should I do – omar haj Nov 13 '20 at 20:07
@ocrdu I'll try – omar haj Nov 13 '20 at 20:08
No that's ain't right . same result – omar haj Nov 13 '20 at 20:10
I don't even know if my answer is the required answer for the question I posted – omar haj Nov 13 '20 at 20:11
3

You could try doubles instead of floats, but still, this shows nicely that the precision of floats is limited, and so is the precision of the math. Floats can do 0.1 + 0.2 = 0.30000000000000004. We all have to live with that. – ocrdu Nov 13 '20 at 20:18
Suggest [Sin and Cos give unexpected results for well-known angles](https://stackoverflow.com/a/31525208/2410359) – chux - Reinstate Monica Nov 14 '20 at 16:50
1

Does this answer your question? [Sin and Cos give unexpected results for well-known angles](https://stackoverflow.com/questions/31502120/sin-and-cos-give-unexpected-results-for-well-known-angles) Key idea: reduce range in degrees first, then convert to radians. – chux - Reinstate Monica Nov 14 '20 at 16:50

Write a program to compute the value of sin(x) using built-in function and using user _define function

0 Answers0