When calculating impulse, the first step is to break the signal into two signals which only contain positive or negative values.

Note that this script makes use of the Current_Signal function within Evaluate Expression.

! Set all frames for all three components to DATA NOT FOUND for any frame
!   ABOVE zero

Evaluate_Expression
/EXPRESSION= ( CURRENT_SIGNAL < 0 ) / ( CURRENT_SIGNAL < 0 ) * CURRENT_SIGNAL
/SIGNAL_TYPES=LINK_MODEL_BASED
/SIGNAL_FOLDER=ORIGINAL
/SIGNAL_NAMES=RGRF+LGRF
! /RESULT_TYPES=DERIVED
/RESULT_FOLDERS=IMPULSE
/RESULT_NAME=_Neg
/APPLY_AS_SUFFIX_TO_SIGNAL_NAME=TRUE
;

! Set all frames for all three components to DATA NOT FOUND for any frame
!   BELOW zero 

Evaluate_Expression
/EXPRESSION=( CURRENT_SIGNAL > 0 ) / ( CURRENT_SIGNAL > 0 ) * CURRENT_SIGNAL
/SIGNAL_TYPES=LINK_MODEL_BASED
/SIGNAL_FOLDER=ORIGINAL
/SIGNAL_NAMES=RGRF+LGRF
! /RESULT_TYPES=DERIVED
/RESULT_FOLDERS=IMPULSE
/RESULT_NAME=_Pos
/APPLY_AS_SUFFIX_TO_SIGNAL_NAME=TRUE
;

! Integrate over stance

Metric_Integrate
/RESULT_METRIC_FOLDER=IMPULSE
/RESULT_METRIC_NAME=
/APPLY_AS_SUFFIX_TO_SIGNAL_NAME=TRUE
/SIGNAL_TYPES=DERIVED+DERIVED
/SIGNAL_FOLDER=IMPULSE+IMPULSE
/SIGNAL_NAMES=RGRF_Neg+RGRF_Pos
/COMPONENT_SEQUENCE=ALL
/EVENT_SEQUENCE=RON+ROFF
/EXCLUDE_EVENTS=
/SEQUENCE_PERCENT_START=
/SEQUENCE_PERCENT_END=
! /GENERATE_MEAN_AND_STDDEV=TRUE
! /APPEND_TO_EXISTING_VALUES=FALSE
;

Metric_Integrate
/RESULT_METRIC_FOLDER=IMPULSE
/RESULT_METRIC_NAME=
/APPLY_AS_SUFFIX_TO_SIGNAL_NAME=TRUE
/SIGNAL_TYPES=DERIVED+DERIVED
/SIGNAL_FOLDER=IMPULSE+IMPULSE
/SIGNAL_NAMES=LGRF_Neg+LGRF_Pos
/COMPONENT_SEQUENCE=ALL
/EVENT_SEQUENCE=LON+LOFF
/EXCLUDE_EVENTS=
/SEQUENCE_PERCENT_START=
/SEQUENCE_PERCENT_END=
! /GENERATE_MEAN_AND_STDDEV=TRUE
! /APPEND_TO_EXISTING_VALUES=FALSE
;