double atan(double x); arc tangent 계산
float atanf(float x); arc tangent 계산
long double atanl(long double x); arc tangent 계산
입력 매개 변수 리스트
x tangent 값
반환 값
arc tangent 값
사용 예
//C언어 표준 라이브러리 함수 가이드
//double atan(double x); arc tangent 계산
//float atanf(float x); arc tangent 계산
//long double atanl(long double x); arc tangent 계산
//0, pi/4, pi/2의 tangent 값과 tangent값의 atangent 값 출력
#include <math.h>
#include <stdio.h>
int main(void)
{
double value;
value = tan(0.0);
printf("tan(%f) = %f\n", 0.0, value);
printf("atan(%f) = %.30f\n", value, atan(value));
printf("atanf(%f) = %.30f\n", value, atanf((float)value));
printf("atanl(%f) = %.30f\n", value, atanl(value));
value = tan(3.141592 / 4);
printf("tan(%f) = %f\n", 3.141592 / 4, value);
printf("atan(%f) = %.30f\n", value, atan(value));
printf("atanf(%f) = %.30f\n", value, atanf((float)value));
printf("atanl(%f) = %.30f\n", value, atanl(value));
value = tan(3.141592 / 2);
printf("tan(%f) = %f\n", 3.141592 / 2, value);
printf("atan(%f) = %.30f\n", value, atan(value));
printf("atanf(%f) = %.30f\n", value, atanf((float)value));
printf("atanl(%f) = %.30f\n", value, atanl(value));
return 0;
}
출력
tan(0.000000) = 0.000000 atan(0.000000) = 0.000000000000000000000000000000 atanf(0.000000) = 0.000000000000000000000000000000 atanl(0.000000) = 0.000000000000000000000000000000 tan(0.785398) = 1.000000 atan(1.000000) = 0.785398000000000040543568502471 atanf(1.000000) = 0.785398006439208984375000000000 atanl(1.000000) = 0.785398000000000040543568502471 tan(1.570796) = 3060023.306953 atan(3060023.306953) = 1.570796000000000081087137004943 atanf(3060023.306953) = 1.570796012878417968750000000000 atanl(3060023.306953) = 1.570796000000000081087137004943