ios - objective-C ；问题

Question

#import "ViewControllerSettings.h"
#define DEGREES(radians) (radians * 180 / M_PI)

NSLog(@"%f", sinFita);

sinFita = asin(DEGREES(sinFita));

NSLog(@"%f", sinFita);

返回

2014-04-20 22:10:09.916 ---[8561:60b] 0.239580
2014-04-20 22:10:09.920 ---[8561:60b] nan

我要求我的答案以 Degreesº 为单位，并且使用了 double。

答案应该是13.86º

Answer 1

asin 参数应该以弧度而不是度为单位，并且 asin 返回的结果也是以弧度为单位，因此您需要按如下方式执行它:

sinFita = DEGREES(asin(sinFita)); // Be aware that sinFita will now be in degrees and not in radians once this line is executed