Commit a66362d6 authored by Joseph Mirabel's avatar Joseph Mirabel
Browse files

[Doc] Add more remarkable identities.

parent c0b034e8
......@@ -207,6 +207,8 @@ PINOCCHIO_LIE_GROUP_PUBLIC_INTERFACE_GENERIC(Derived,typename)
* @param[in] q1 the terminal configuration vector.
*
* @param[out] v the corresponding velocity.
*
* \cheatsheet \f$ q_1 \ominus q_0 = - \left( q_0 \ominus q_1 \right) \f$
*/
template <class ConfigL_t, class ConfigR_t, class Tangent_t>
void difference(const Eigen::MatrixBase<ConfigL_t> & q0,
......@@ -224,6 +226,14 @@ PINOCCHIO_LIE_GROUP_PUBLIC_INTERFACE_GENERIC(Derived,typename)
*
* @param[out] J the Jacobian of the difference operation.
*
* \warning because \f$ q_1 \ominus q_0 = - \left( q_0 \ominus q_1 \right) \f$,
* you may be tempted to write
* \f$ \frac{\partial\ominus}{\partial q_1} = - \frac{\partial\ominus}{\partial q_0} \f$.
* This is **false** in the general case because
* \f$ \frac{\partial\ominus}{\partial q_i} \f$ expects an input velocity relative to frame i.
* See SpecialEuclideanOperationTpl<3,_Scalar,_Options>::dDifference_impl.
*
* \cheatsheet \f$ \frac{\partial\ominus}{\partial q_1} \frac{\partial\oplus}{\partial v} = I \f$
*/
template <ArgumentPosition arg, class ConfigL_t, class ConfigR_t, class JacobianOut_t>
void dDifference(const Eigen::MatrixBase<ConfigL_t> & q0,
......@@ -279,6 +289,8 @@ PINOCCHIO_LIE_GROUP_PUBLIC_INTERFACE_GENERIC(Derived,typename)
*
* @param[in] q0 Configuration 0
* @param[in] q1 Configuration 1
*
* \cheatsheet \f$ q_1 \equiv q_0 \oplus \left( q_1 \ominus q_0 \right) \f$ (\f$\equiv\f$ means equivalent, not equal).
*/
template <class ConfigL_t, class ConfigR_t>
bool isSameConfiguration(const Eigen::MatrixBase<ConfigL_t> & q0,
......
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