In C, tan(30) gives me a negative value! Why?
android, android-ndk, c, cmath, math
Solution
In C, `tan` and other trigonometric functions expect radians as their arguments, not degrees. You can convert degrees to radians:
tan( 30. * M_PI / 180. ) == 0.57735026918962576450914878050196
Problem
I observe that my `tan(float)` function from the `cmath` library is returning a negative value. The following piece of code, when run : ``` #include <cmath> .... // some calculation here gives me a value between 0.0 to 1.0. float tempSpeed = 0.5; float tanValue = tan(tempSpeed * 60); __android_log_print(ANDROID_LOG_INFO, "Log Me", "speed: %f", tanValue); ``` Gives me this result in my Log file: ``` Log Me: speed `-6.4053311966` ``` As far as I remember ``` tan(0.5*60) = tan(30) = 1/squareroot(3); ``` Can someone help me here as in why I am seeing a negative value? Is it related to some floating point size error? Or am I doing something really dumb?