question: public void insertEquationData ( final int index , double [ ] equationData , double [ ] complete ) throws MathIllegalArgumentException { checkIndex ( index ) ; final int begin = start [ index ] ; final int end = start [ index + 1 ] ; final int dimension = end - begin ; if ( complete . length < end ) { throw new MathIllegalArgumentException ( LocalizedCoreFormats . DIMENSIONS_MISMATCH , complete . length , end ) ; } if ( equationData . length != dimension ) { throw new MathIllegalArgumentException ( LocalizedCoreFormats . DIMENSIONS_MISMATCH , equationData . length , dimension ) ; } System . arraycopy ( equationData , 0 , complete , begin , dimension ) ; }
target:  Insert equation data into a complete state or derivative array.