Math

Macros
#define	TRIG_MAX_RATIO   0xffff
	The largest value that can result from a call to sin_lookup or cos_lookup.
#define	TRIG_MAX_ANGLE   0x10000
	Angle value that corresponds to 360 degrees or 2 PI radians.
#define	TRIGANGLE_TO_DEG(trig_angle)   (((trig_angle) * 360) / TRIG_MAX_ANGLE)
	Converts from a fixed point value representation to the equivalent value in degrees.
#define	DEG_TO_TRIGANGLE(angle)   (((angle) * TRIG_MAX_ANGLE) / 360)
	Converts from an angle in degrees to the equivalent fixed point value representation.

Functions
int32_t	sin_lookup (int32_t angle)
	Look-up the sine of the given angle from a pre-computed table.
int32_t	cos_lookup (int32_t angle)
	Look-up the cosine of the given angle from a pre-computed table.
int32_t	atan2_lookup (int16_t y, int16_t x)
	Look-up the arctangent of a given x, y pair.

Detailed Description

Macro Definition Documentation

DEG_TO_TRIGANGLE

#define DEG_TO_TRIGANGLE

(

angle

)

(((angle) * TRIG_MAX_ANGLE) / 360)

Converts from an angle in degrees to the equivalent fixed point value representation.

See also

TRIGANGLE_TO_DEG

TRIG_MAX_ANGLE

Parameters

angle

Angle in degrees.

Returns

Angle, scaled so that TRIG_MAX_ANGLE is 360 degrees.

TRIG_MAX_ANGLE

#define TRIG_MAX_ANGLE   0x10000

Angle value that corresponds to 360 degrees or 2 PI radians.

See also

sin_lookup

cos_lookup

TRIG_MAX_RATIO

#define TRIG_MAX_RATIO   0xffff

The largest value that can result from a call to sin_lookup or cos_lookup.

For a code example, see the detailed description at the top of this chapter: Math

TRIGANGLE_TO_DEG

#define TRIGANGLE_TO_DEG

(

trig_angle

)

(((trig_angle) * 360) / TRIG_MAX_ANGLE)

Converts from a fixed point value representation to the equivalent value in degrees.

See also

DEG_TO_TRIGANGLE

TRIG_MAX_ANGLE

Parameters

trig_angle

Angle, scaled so that TRIG_MAX_ANGLE is 360 degrees.

Returns

Angle in degrees.

Function Documentation

atan2_lookup()

int32_t atan2_lookup	(	int16_t	y,
		int16_t	x
	)

Look-up the arctangent of a given x, y pair.

The angle value is scaled linearly, such that a value of 0x10000 corresponds to 360 degrees or 2 PI radians.

Parameters

y	Y coordinate.
x	X coordinate.

Returns

Angle of the point (x, y) counter-clockwise from the positive x axis, from 0 up to but not including TRIG_MAX_ANGLE.

cos_lookup()

int32_t cos_lookup

(

int32_t

angle

)

Look-up the cosine of the given angle from a pre-computed table.

This is equivalent to calling sin_lookup(angle + TRIG_MAX_ANGLE / 4).

Parameters

angle

The angle for which to compute the cosine. The angle value is scaled linearly, such that a value of 0x10000 corresponds to 360 degrees or 2 PI radians.

Returns

Cosine of angle, scaled so that 1 is TRIG_MAX_RATIO.

sin_lookup()

int32_t sin_lookup

(

int32_t

angle

)

Look-up the sine of the given angle from a pre-computed table.

Parameters

angle

The angle for which to compute the sine. The angle value is scaled linearly, such that a value of 0x10000 corresponds to 360 degrees or 2 PI radians.

Returns

Sine of angle, scaled so that 1 is TRIG_MAX_RATIO.