question: public double [ ] extractParameterJacobian ( final ODEState state , final String pName ) { final double [ ] p = state . getSecondaryState ( index ) ; final double [ ] dYdP = new double [ jode . getDimension ( ) ] ; int i = jode . getDimension ( ) * jode . getDimension ( ) ; for ( final String knownParameter : jode . getParametersNames ( ) ) { if ( pName . equals ( knownParameter ) ) { System . arraycopy ( p , i , dYdP , 0 , jode . getDimension ( ) ) ; break ; } i += jode . getDimension ( ) ; } return dYdP ; }
target:  Extract the Jacobian matrix with respect to one parameter.