Fix quaternion typos.

PiperOrigin-RevId: 453203844
Change-Id: I7d788c21bb00b7746f941fb2cf755f0b046e35f2

doc/APIreference.rst

@@ -543,7 +543,7 @@ mjtSensor
        mjSENS_ACTUATORFRC,             // scalar actuator force
 
        // sensors related to ball joints
-       mjSENS_BALLQUAT,                // 4D ball joint quaterion
+       mjSENS_BALLQUAT,                // 4D ball joint quaternion
        mjSENS_BALLANGVEL,              // 3D ball joint angular velocity
 
        // joint and tendon limit sensors, in constraint space
@@ -3162,7 +3162,7 @@ Numeric constants
 |                  |        | array sizes which we have not fully settled. There may be reasons to increase them in  |
 |                  |        | the future, so as to accommodate extra parameters needed for more elaborate            |
 |                  |        | computations. This is why we maintain them as symbolic constants that can be easily    |
-|                  |        | changed, as opposed to the array size for representing quaterions for example - which  |
+|                  |        | changed, as opposed to the array size for representing quaternions for example - which |
 |                  |        | has no reason to change.                                                               |
 +------------------+--------+----------------------------------------------------------------------------------------+
 | mjNDYN           | 10     | The maximal number of real-valued parameters used to define the activation dynamics of |
@@ -4549,7 +4549,7 @@ mj_normalizeQuat
 
    void mj_normalizeQuat(const mjModel* m, mjtNum* qpos);
 
-Normalize all quaterions in qpos-type vector.
+Normalize all quaternions in qpos-type vector.
 
 .. _mj_local2Global:
 
@@ -6184,7 +6184,7 @@ mju_mat2Quat
 
    void mju_mat2Quat(mjtNum quat[4], const mjtNum mat[9]);
 
-Convert 3D rotation matrix to quaterion.
+Convert 3D rotation matrix to quaternion.
 
 .. _mju_derivQuat:
 
@@ -6206,7 +6206,7 @@ mju_quatIntegrate
 
    void mju_quatIntegrate(mjtNum quat[4], const mjtNum vel[3], mjtNum scale);
 
-Integrate quaterion given 3D angular velocity.
+Integrate quaternion given 3D angular velocity.
 
 .. _mju_quatZ2Vec:
 

doc/XMLreference.rst

@@ -2783,7 +2783,7 @@ subelements. The file format starts with a header of 4 integers: nvertex, ntexco
 the same as in meshes, and specify the total number of vertices, texture coordinate pairs, and triangle faces in the
 skin. ntexcoord can be zero or equal to nvertex. nbone specifies the number of MuJoCo bodies that will be used as
 bones in the skin. The header is followed by the vertex, texcoord and face data, followed by a specification for each
-bone. The bone specification contains the name of the corresponding model body, 3D bind position, 4D bind quaterion,
+bone. The bone specification contains the name of the corresponding model body, 3D bind position, 4D bind quaternion,
 number of vertices influenced by the bone, and the vertex index array and weight array. Body names are represented as
 fixed-length character arrays and are expected to be 0-terminated. Characters after the first 0 are ignored. The
 contents of the SKN file are:
@@ -5020,7 +5020,7 @@ bodies whose center of mass is of interest.
 :at:`objname`: :at-val:`string, required`
    Name of the MuJoCo object to which the sensor is attached.
 :at:`datatype`: :at-val:`[real, positive, axis, quaternion], required`
-   The type of output generated by this sensor. "axis" means a unit-length 3D vector. "quat" means a unit quaterion.
+   The type of output generated by this sensor. "axis" means a unit-length 3D vector. "quat" means a unit quaternion.
    These need to be declared because when MuJoCo adds noise, it must respect the vector normalization. "real" means a
    generic array (or scalar) of real values to which noise can be added independently.
 :at:`needstage`: :at-val:`[pos, vel, acc], required`

doc/programming.rst

@@ -1136,7 +1136,7 @@ the standard convention, we set A_rowadr[r] = r*n. MuJoCo uses sparse matrices i
 To represent 3D orientations and rotations, MuJoCo uses unit quaternions - namely 4D unit vectors arranged as q = (w,
 x, y, z). Here (x, y, z) is the rotation axis unit vector scaled by sin(a/2), where a is the rotation angle in
 radians, and w = cos(a/2). Thus the quaternion corresponding to a null rotation is (1, 0, 0, 0). This is the default
-setting of all quaterions in MJCF.
+setting of all quaternions in MJCF.
 
 MuJoCo also uses 6D spatial vectors internally. These are quantities in mjData prefixed with 'c', namely cvel, cacc,
 cdot, etc. They are spatial motion and force vectors that combine a 3D rotational component followed by a 3D