euler.c File Reference

#include "attitude/euler.h"
#include <math.h>
#include <stddef.h>

Go to the source code of this file.

Functions
void	euler_to_dcm (const EulerAngles *e, double dcm[3][3])
	Convert Euler angles to a direction cosine matrix.
int	euler_to_dcm_checked (const EulerAngles *e, double dcm[3][3])
	Checked Euler-to-DCM conversion.
void	euler_to_quaternion (const EulerAngles *e, double q[4])
	Convert Euler angles to a quaternion.
int	euler_to_quaternion_checked (const EulerAngles *e, double q[4])
	Checked Euler-to-quaternion conversion.

Function Documentation

euler_to_dcm()

void euler_to_dcm	(	const EulerAngles *	e,
		double	dcm[3][3]
	)

Convert Euler angles to a direction cosine matrix.

Parameters

e	Euler angle container in radians.
dcm	Output \(3\times3\) matrix (row-major).

Definition at line 41 of file euler.c.

                                                          {
    if (!euler_to_dcm_checked(e, dcm)) {
        set_nan_matrix(dcm);
    }
}

euler_to_dcm_checked()

int euler_to_dcm_checked	(	const EulerAngles *	e,
		double	dcm[3][3]
	)

Checked Euler-to-DCM conversion.

Returns

1 on success, 0 for null pointers, non-finite angles, or an unsupported order.

Definition at line 16 of file euler.c.

                                                                 {
    if (e == NULL || dcm == NULL || e->order != EULER_ZYX ||
        !isfinite(e->roll) || !isfinite(e->pitch) || !isfinite(e->yaw)) {
        return 0;
    }
 
    double cr = cos(e->roll);
    double sr = sin(e->roll);
    double cp = cos(e->pitch);
    double sp = sin(e->pitch);
    double cy = cos(e->yaw);
    double sy = sin(e->yaw);
 
    dcm[0][0] = cy*cp;
    dcm[0][1] = cy*sp*sr - sy*cr;
    dcm[0][2] = cy*sp*cr + sy*sr;
    dcm[1][0] = sy*cp;
    dcm[1][1] = sy*sp*sr + cy*cr;
    dcm[1][2] = sy*sp*cr - cy*sr;
    dcm[2][0] = -sp;
    dcm[2][1] = cp*sr;
    dcm[2][2] = cp*cr;
    return 1;
}

euler_to_quaternion()

void euler_to_quaternion	(	const EulerAngles *	e,
		double	q[4]
	)

Convert Euler angles to a quaternion.

Parameters

e	Euler angle container in radians.
q	Output quaternion in \([w, x, y, z]\) order.

Definition at line 67 of file euler.c.

                                                            {
    if (!euler_to_quaternion_checked(e, q) && q != NULL) {
        for (int index = 0; index < 4; ++index) {
            q[index] = NAN;
        }
    }
}

euler_to_quaternion_checked()

int euler_to_quaternion_checked	(	const EulerAngles *	e,
		double	q[4]
	)

Checked Euler-to-quaternion conversion.

Returns

1 on success, 0 for null pointers, non-finite angles, or an unsupported order.

Definition at line 47 of file euler.c.

                                                                   {
    if (e == NULL || q == NULL || e->order != EULER_ZYX ||
        !isfinite(e->roll) || !isfinite(e->pitch) || !isfinite(e->yaw)) {
        return 0;
    }
 
    double cr = cos(e->roll/2.0);
    double sr = sin(e->roll/2.0);
    double cp = cos(e->pitch/2.0);
    double sp = sin(e->pitch/2.0);
    double cy = cos(e->yaw/2.0);
    double sy = sin(e->yaw/2.0);
 
    q[0] = cr*cp*cy + sr*sp*sy; // w
    q[1] = sr*cp*cy - cr*sp*sy; // x
    q[2] = cr*sp*cy + sr*cp*sy; // y
    q[3] = cr*cp*sy - sr*sp*cy; // z
    return 1;
}