Difference between revisions of "cpp/numeric/math/acos"

Latest revision as of 08:37, 28 June 2023

Defined in header `<cmath>`
	(1)
float acos ( float num ); double acos ( double num ); long double acos ( long double num );			(until C++23)
/* floating-point-type / acos ( / floating-point-type */ num );			(since C++23) (constexpr since C++26)
float acosf( float num );		(2)	(since C++11) (constexpr since C++26)
long double acosl( long double num );		(3)	(since C++11) (constexpr since C++26)
Additional overloads (since C++11)
Defined in header `<cmath>`
template< class Integer > double acos ( Integer num );		(A)	(constexpr since C++26)

1-3) Computes the principal value of the arc cosine of num. The library provides overloads of std::acos for all cv-unqualified floating-point types as the type of the parameter.(since C++23)

A) Additional overloads are provided for all integer types, which are treated as double.

(since C++11)

#include <cerrno>
#include <cfenv>
#include <cmath>
#include <cstring>
#include <iostream>
 
// #pragma STDC FENV_ACCESS ON
 
int main()
{
    std::cout << "acos(-1) = " << std::acos(-1) << '\n'
              << "acos(0.0) = " << std::acos(0.0) << '\n'
              << "2*acos(0.0) = " << 2 * std::acos(0) << '\n'
              << "acos(0.5) = " << std::acos(0.5) << '\n'
              << "3*acos(0.5) = " << 3 * std::acos(0.5) << '\n'
              << "acos(1) = " << std::acos(1) << '\n';
 
    // error handling
    errno = 0;
    std::feclearexcept(FE_ALL_EXCEPT);
 
    std::cout << "acos(1.1) = " << std::acos(1.1) << '\n';
 
    if (errno == EDOM)
        std::cout << "    errno == EDOM: " << std::strerror(errno) << '\n';
    if (std::fetestexcept(FE_INVALID))
        std::cout << "    FE_INVALID raised" << '\n';
}

Output:

acos(-1) = 3.14159
acos(0.0) = 1.5708
2*acos(0.0) = 3.14159
acos(0.5) = 1.0472
3*acos(0.5) = 3.14159
acos(1) = 0
acos(1.1) = nan
    errno == EDOM: Numerical argument out of domain
    FE_INVALID raised

[edit] See also

asinasinfasinl (C++11)(C++11)	computes arc sine (${\small\arcsin{x}}$ $arcsin(x)$ ) (function) [edit]
atanatanfatanl (C++11)(C++11)	computes arc tangent (${\small\arctan{x}}$ $arctan(x)$ ) (function) [edit]
atan2atan2fatan2l (C++11)(C++11)	arc tangent, using signs to determine quadrants (function) [edit]
coscosfcosl (C++11)(C++11)	computes cosine (${\small\cos{x}}$ $cos(x)$ ) (function) [edit]
acos(std::complex) (C++11)	computes arc cosine of a complex number (${\small\arccos{z}}$ $arccos(z)$ ) (function template) [edit]
acos(std::valarray)	applies the function std::acos to each element of valarray (function template) [edit]
C documentation for acos

@@ Line 1: / Line 1: @@
-{{cpp/title|acos}}
+{{cpp/title|acos|acosf|acosl}}
-{{cpp/numeric/math/sidebar}}
+{{cpp/numeric/math/navbar}}
-{{ddcl list begin}}
+{{cpp/numeric/math/declarations
-{{ddcl list header | cmath}}
+|family=acos
-{{ddcl list item |
+|param1=num
-float       acos( float arg );
+|constexpr_since=26
+|desc=Computes the principal value of the arc cosine of {{c|num}}.
 }}
-{{ddcl list item |
-double      acos( double arg );
-}}
-{{ddcl list item |
-long double acos( long double arg );
-}}
-{{ddcl list end}}
-Computes arc cosine of {{tt|arg}}
-<!-- ======== -->
 ===Parameters===
-{{param list begin}}
+{{par begin}}
-{{param list item | arg | floating point value}}
+{{par|num|floating-point or integer value}}
-{{param list end}}
+{{par end}}
-<!-- ======== -->
 ===Return value===
+If no errors occur, the arc cosine of {{c|num}} ({{math|arccos(num)}}) in the range {{math|[0, &pi;]}}, is returned.
-arc sine of {{tt|arg}} in radians in the range of {{tt|[0; &pi;]}} radians.
+If a domain error occurs, an implementation-defined value is returned (NaN where supported).
-Domain error occurs if {{tt|arg}} is outside the range {{tt|[-1.0; 1.0]}}. {{cpp|NAN}} is returned in that case.
+If a range error occurs due to underflow, the correct result (after rounding) is returned.
+===Error handling===
+Errors are reported as specified in {{lc|math_errhandling}}.
+Domain error occurs if {{c|num}} is outside the range {{closed range|-1.0|1.0}}.
+If the implementation supports IEEE floating-point arithmetic (IEC 60559),
+* If the argument is {{math|+1}}, the value {{tt|+0}} is returned.
+* If {{math|{{!}}num{{!}} > 1}}, a domain error occurs and NaN is returned.
+* if the argument is NaN, NaN is returned.
+===Notes===
+{{cpp/numeric/math/additional integer overload note|acos}}
+===Example===
+{{example
+|code=
+#include <cerrno>
+#include <cfenv>
+#include <cmath>
+#include <cstring>
+#include <iostream>
+// #pragma STDC FENV_ACCESS ON
+int main()
+{
+    std::cout << "acos(-1) = " << std::acos(-1) << '\n'
+              << "acos(0.0) = " << std::acos(0.0) << '\n'
+              << "2*acos(0.0) = " << 2 * std::acos(0) << '\n'
+              << "acos(0.5) = " << std::acos(0.5) << '\n'
+              << "3*acos(0.5) = " << 3 * std::acos(0.5) << '\n'
+              << "acos(1) = " << std::acos(1) << '\n';
+    // error handling
+    errno = 0;
+    std::feclearexcept(FE_ALL_EXCEPT);
+    std::cout << "acos(1.1) = " << std::acos(1.1) << '\n';
+    if (errno == EDOM)
+        std::cout << "    errno == EDOM: " << std::strerror(errno) << '\n';
+    if (std::fetestexcept(FE_INVALID))
+        std::cout << "    FE_INVALID raised" << '\n';
+}
+|output=
+acos(-1) = 3.14159
+acos(0.0) = 1.5708
+*acos(0.0) = 3.14159
+acos(0.5) = 1.0472
+*acos(0.5) = 3.14159
+acos(1) = 0
+acos(1.1) = nan
+    errno == EDOM: Numerical argument out of domain
+    FE_INVALID raised
+}}
-<!-- ======== -->
 ===See also===
+{{dsc begin}}
+{{dsc inc|cpp/numeric/math/dsc asin}}
+{{dsc inc|cpp/numeric/math/dsc atan}}
+{{dsc inc|cpp/numeric/math/dsc atan2}}
+{{dsc inc|cpp/numeric/math/dsc cos}}
+{{dsc inc|cpp/numeric/complex/dsc acos}}
+{{dsc inc|cpp/numeric/valarray/dsc acos}}
+{{dsc see c|c/numeric/math/acos}}
+{{dsc end}}
-{{dcl list begin}}
+{{langlinks|de|es|fr|it|ja|pl|pt|ru|zh}}
-{{dcl list template | cpp/numeric/math/dcl list asin}}
-{{dcl list template | cpp/numeric/math/dcl list atan}}
-{{dcl list template | cpp/numeric/math/dcl list atan2}}
-{{dcl list template | cpp/numeric/math/dcl list cos}}
-{{dcl list end}}

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Difference between revisions of "cpp/numeric/math/acos"

Latest revision as of 08:37, 28 June 2023

Contents

[edit] Parameters

[edit] Return value

[edit] Error handling

[edit] Notes

[edit] Example

[edit] See also

Navigation

Toolbox

asinasinfasinl (C++11)(C++11)	computes arc sine (\({\small\arcsin{x}}\) $arcsin(x)$ ) (function) [edit]
atanatanfatanl (C++11)(C++11)	computes arc tangent (\({\small\arctan{x}}\) $arctan(x)$ ) (function) [edit]
atan2atan2fatan2l (C++11)(C++11)	arc tangent, using signs to determine quadrants (function) [edit]
coscosfcosl (C++11)(C++11)	computes cosine (\({\small\cos{x}}\) $cos(x)$ ) (function) [edit]
acos(std::complex) (C++11)	computes arc cosine of a complex number (\({\small\arccos{z}}\) $arccos(z)$ ) (function template) [edit]
acos(std::valarray)	applies the function std::acos to each element of valarray (function template) [edit]
C documentation for acos