- Qt 5.15
- Qt Core
- <QtMath> - Generic Math Functions
- Qt 5.15.18 Reference Documentation

# <QtMath> - Generic Math Functions

The <QtMath> header file provides various math functions. More...

Header: | #include <QtMath>

## Functions

qreal | qAcos(qreal v)
qreal | qAsin(qreal v)
qreal | qAtan2(qreal y, qreal x)
qreal | qAtan(qreal v)
int | qCeil(qreal v)
qreal | qCos(qreal v)
float | qDegreesToRadians(float degrees)
double | qDegreesToRadians(double degrees)
qreal | qExp(qreal v)
qreal | qFabs(qreal v)
int | qFloor(qreal v)
qreal | qLn(qreal v)
quint32 | qNextPowerOfTwo(quint32 value)
quint64 | qNextPowerOfTwo(quint64 value)
quint32 | qNextPowerOfTwo(qint32 value)
quint64 | qNextPowerOfTwo(qint64 value)
qreal | qPow(qreal x, qreal y)
float | qRadiansToDegrees(float radians)
double | qRadiansToDegrees(double radians)
qreal | qSin(qreal v)
qreal | qSqrt(qreal v)
qreal | qTan(qreal v)

## Detailed Description

These functions are partly convenience definitions for basic math operations not available in the C or Standard Template Libraries.

The header also ensures some constants specified in POSIX, but not present in C++ standards (so absent from <math.h> on some platforms), are defined:

Constant | Description
--- | ---
`M_E` | The base of the natural logarithms, e = exp(1)
`M_LOG2E` | The base-two logarithm of e
`M_LOG10E` | The base-ten logarithm of e
`M_LN2` | The natural logarithm of two
`M_LN10` | The natural logarithm of ten
`M_PI` | The ratio of a circle's circumference to diameter, π
`M_PI_2` | Half M_PI, π / 2
`M_PI_4` | Quarter M_PI, π / 4
`M_1_PI` | The inverse of M_PI, 1 / π
`M_2_PI` | Twice the inverse of M_PI, 2 / π
`M_2_SQRTPI` | Two divided by the square root of pi, 2 / √π
`M_SQRT2` | The square root of two, √2
`M_SQRT1_2` | The square roof of half, 1 / √2

## Function Documentation

### qreal qAcos(qreal v)

Returns the arccosine of v as an angle in radians. Arccosine is the inverse operation of cosine.

See also qAtan(), qAsin(), and qCos().

### qreal qAsin(qreal v)

Returns the arcsine of v as an angle in radians. Arcsine is the inverse operation of sine.

See also qSin(), qAtan(), and qAcos().

### qreal qAtan2(qreal y, qreal x)

Returns the arctangent of a point specified by the coordinates y and x. This function will return the angle (argument) of that point.

See also qAtan().

### qreal qAtan(qreal v)

Returns the arctangent of v as an angle in radians. Arctangent is the inverse operation of tangent.

See also qTan(), qAcos(), and qAsin().

### int qCeil(qreal v)

Return the ceiling of the value v.

The ceiling is the smallest integer that is not less than v. For example, if v is 41.2, then the ceiling is 42.

See also qFloor().

### qreal qCos(qreal v)

Returns the cosine of an angle v in radians.

See also qSin() and qTan().

### float qDegreesToRadians(float degrees)

This function converts the degrees in float to radians.

Example:

     float degrees = 180.0f
     float radians = qDegreesToRadians(degrees)

This function was introduced in Qt 5.1.

See also qRadiansToDegrees().

### double qDegreesToRadians(double degrees)

This function converts the degrees in double to radians.

Example:

     double degrees = 180.0
     double radians = qDegreesToRadians(degrees)

This function was introduced in Qt 5.1.

See also qRadiansToDegrees().

### qreal qExp(qreal v)

Returns the exponential function of `e` to the power of v.

See also qLn().

### qreal qFabs(qreal v)

Returns the absolute value of v as a qreal.

### int qFloor(qreal v)

Return the floor of the value v.

The floor is the largest integer that is not greater than v. For example, if v is 41.2, then the floor is 41.

See also qCeil().

### qreal qLn(qreal v)

Returns the natural logarithm of v. Natural logarithm uses base e.

See also qExp().

### quint32 qNextPowerOfTwo(quint32 value)

This function returns the nearest power of two greater than value. For 0 it returns 1, and for values larger than or equal to 2^31 it returns 0.

This function was introduced in Qt 5.4.

### quint64 qNextPowerOfTwo(quint64 value)

This function returns the nearest power of two greater than value. For 0 it returns 1, and for values larger than or equal to 2^63 it returns 0.

This function was introduced in Qt 5.4.

### quint32 qNextPowerOfTwo(qint32 value)

This is an overloaded function.

This function returns the nearest power of two greater than value. For negative values it returns 0.

This function was introduced in Qt 5.4.

### quint64 qNextPowerOfTwo(qint64 value)

This is an overloaded function.

This function returns the nearest power of two greater than value. For negative values it returns 0.

This function was introduced in Qt 5.4.

### qreal qPow(qreal x, qreal y)

Returns the value of x raised to the power of y. That is, x is the base and y is the exponent.

See also qSqrt().

### float qRadiansToDegrees(float radians)

This function converts the radians in float to degrees.

Example:

     float radians = float(M_PI)
     float degrees = qRadiansToDegrees(radians)

This function was introduced in Qt 5.1.

See also qDegreesToRadians().

### double qRadiansToDegrees(double radians)

This function converts the radians in double to degrees.

Example:

     double radians = M_PI
     double degrees = qRadiansToDegrees(radians)

This function was introduced in Qt 5.1.

See also qDegreesToRadians().

### qreal qSin(qreal v)

Returns the sine of the angle v in radians.

See also qCos() and qTan().

### qreal qSqrt(qreal v)

Returns the square root of v. This function returns a NaN if v is a negative number.

See also qPow().

### qreal qTan(qreal v)

Returns the tangent of an angle v in radians.

See also qSin() and qCos().