# the preceding example could have been written in fewer
# lines as follows (although the SPOT rule is broken)
end_time = 5
dt = 1/20
# PRNT t heaviside(t-1)-heaviside(t-3) lag(heaviside(t-1)-heaviside(t-3),1.234)
y = lag(heaviside(t-1)-heaviside(t-3),1.234)
IF done
 PRINT %.2f y
ENDIF