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Result of sin function differs?

P: n/a
asd
Hello all.

I was doing some kind of development and in the test file I have something
like this:

///// Test File /////
double x = sin(45);

The output for that statement is:

///// Output Test File /////
0.707107
Unfortunately the output in my system differs from the one in the test
file.

I run the following example in my system:

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout << sin(45) << endl; // prints 0.850904

return 0;
}

The example above prints 0.850904 in my system. In addition to that, my
calculator says sin(45) is 0.707107, while calculator at google says that
it is 0.850904.

I am just curious if I am doing something wrong.
Thanks a lot.
Mar 24 '07 #1
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8 Replies


P: n/a
sin(45 degree) is approximately 0.707107,
sin(45 in radian) is approximately 0.850904.

My 2 cents.

Stephen Wong @ Hong Kong

On Sat, 24 Mar 2007, asd wrote:
Hello all.

I was doing some kind of development and in the test file I have something
like this:

///// Test File /////
double x = sin(45);

The output for that statement is:

///// Output Test File /////
0.707107
Unfortunately the output in my system differs from the one in the test
file.

I run the following example in my system:

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout << sin(45) << endl; // prints 0.850904

return 0;
}

The example above prints 0.850904 in my system. In addition to that, my
calculator says sin(45) is 0.707107, while calculator at google says that
it is 0.850904.

I am just curious if I am doing something wrong.
Thanks a lot.
Mar 24 '07 #2

P: n/a
asd wrote:
Hello all.

I was doing some kind of development and in the test file I have something
like this:

///// Test File /////
double x = sin(45);

The output for that statement is:

///// Output Test File /////
0.707107
Unfortunately the output in my system differs from the one in the test
file.

I run the following example in my system:

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout << sin(45) << endl; // prints 0.850904

return 0;
}

The example above prints 0.850904 in my system. In addition to that, my
calculator says sin(45) is 0.707107, while calculator at google says that
it is 0.850904.
You are confusing different ways of measuring angles. A half of a right
angle can be specified as 45 deg or as Pi/8 rad. In the above computations,
the number 45 sometimes is interpreted as deg and sometimes as rad.
Best

Kai-Uwe Bux
Mar 24 '07 #3

P: n/a

"asd" <no****@nospam.comwrote in message
news:pa****************************@nospam.com...
Hello all.

I was doing some kind of development and in the test file I have something
like this:

///// Test File /////
double x = sin(45);

The output for that statement is:

///// Output Test File /////
0.707107
Unfortunately the output in my system differs from the one in the test
file.

I run the following example in my system:

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout << sin(45) << endl; // prints 0.850904

return 0;
}

The example above prints 0.850904 in my system. In addition to that, my
calculator says sin(45) is 0.707107, while calculator at google says that
it is 0.850904.

I am just curious if I am doing something wrong.
This program should explain.

#include <cmath>
#include <iostream>
#include <string>

const double pi = 3.1415926;

int main()
{
double degrees = 45.0;
// There are 2 pi radians in a circle.
// There are 360 degrees in a circle.
double radians = ( 2.0*pi) / 360.0 * degrees;

// std::sin expects input as radians
std::cout << std::sin( radians ) << "\n";

std::string wait;
std::getline( std::cin, wait );

}
Mar 24 '07 #4

P: n/a
asd
Thank you so much for all of your answers.

Now I am struggling with asin.

the test file has:
asin(.5);

// test output
30

// My output with radian conversion
0.00872676

// without radian conversion
0.523599

I would be glad if you could also help this one.
Thanks alot.
Mar 24 '07 #5

P: n/a
"asd" <no****@nospam.comwrote in message
news:pa****************************@nospam.com...
Thank you so much for all of your answers.

Now I am struggling with asin.

the test file has:
asin(.5);

// test output
30

// My output with radian conversion
0.00872676

// without radian conversion
0.523599

I would be glad if you could also help this one.
Thanks alot.
comments for asin in VC++ is:

The units of the returned elements are in radians.
The return value is a principal value between +pi/2 and -pi/2 that is
consistent with the sine value input.

No way you're going to get a value of 30 out of that unless you multiply it
by some factor. I don't know where they get 30 from.

Mar 24 '07 #6

P: n/a
asd
On Sat, 24 Mar 2007 15:31:09 -0700, Jim Langston wrote:
"asd" <no****@nospam.comwrote in message
news:pa****************************@nospam.com...
>Thank you so much for all of your answers.

Now I am struggling with asin.

the test file has:
asin(.5);

// test output
30

// My output with radian conversion
0.00872676

// without radian conversion
0.523599

I would be glad if you could also help this one.
Thanks alot.

comments for asin in VC++ is:

The units of the returned elements are in radians.
The return value is a principal value between +pi/2 and -pi/2 that is
consistent with the sine value input.

No way you're going to get a value of 30 out of that unless you multiply it
by some factor. I don't know where they get 30 from.

Thank you so much Jim, it worked.

Mar 25 '07 #7

P: n/a
Kai-Uwe Bux <jk********@gmx.netwrote:
You are confusing different ways of measuring angles. A half of a right
angle can be specified as 45 deg or as Pi/8 rad.
I think you mean Pi/4 rad.

--
Marcus Kwok
Replace 'invalid' with 'net' to reply
Mar 26 '07 #8

P: n/a
Marcus Kwok wrote:
Kai-Uwe Bux <jk********@gmx.netwrote:
>You are confusing different ways of measuring angles. A half of a right
angle can be specified as 45 deg or as Pi/8 rad.

I think you mean Pi/4 rad.
Sort of: I think, I meant 2*Pi/8 :-)
Thanks

Kai-Uwe Bux
Mar 26 '07 #9

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