On Oct 1, 2008, at 12:29 AM, Michael Robinson wrote:
sin(90); returns 0 as well. When I use Apple's Calculator and ask it
to tell me the result of sin(90), it gives me 1.
The C function sin() takes radians as its parameter. In order to use
degrees you need to multiply by M_PI and divide by 180:
int angle = 90;
float result = sin(angle * M_PI / 180);
One other thing you have to remember is that when you are doing
operations with integers your result will be an integer. Doing:
float result = 90 / 180;
Will give you a value of 0. This is because a value of 0.5 will have
the fractional part dropped to make it an integer. In order to retain
the fractional part I need to make one of the values into a type that
preserves the fractional part:
float result = 90.0 / 180;
or
float result = (float)90 / 180;
Adding a decimal point or using a cast makes one of the values into a
type that preserves the fractional part. Now the result of any
operations will retain the fraction. In my example the constant M_PI
is already a fractional type so I didn't need to do any more work to
make sure the fraction was retained.
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