BSL PRO Software Guide - Biopac

166 Part DMEASUREMENT Area EXPLANATIONUses:All points ofselected areaThis plotgraphicallyrepresents theIntegralcalculation.The area of theshaded portionis the result.Integral is expressed in terms of (amplitude units multiplied by horizontalunits) and calculated using the following formula.n 1 i 1Integral = fxif xi1Where:n – number of samples;i – index (i = 1.n-1);xi2Lin_regMinimum area:2 samplesUses:All points ofselected areaxi, x i 1 - values of two neighboring points at horizontal axis (1x – thefirst point, xn– the last point);f xi, f x i 1 - values of two neighboring points of a curve (verticalaxis);Xx i - horizontal sample interval;n 1X xn x 1- horizontal distance of increase at horizontal axis.Results: The Integral calculation can return a negative value if theselected area of the waveform extends below zero.Units: Volts – sec.Sample data file: “ValidateMeasurements.ACQ”Result: 0.300 Volts -sec.(for first 6 sample points) and –0.155 Volts -sec.(for last 6 sample points – the wave below zero).Linear regression is a better method to calculate the slope when youhave noisy, erratic data.Lin_reg computes the non-standard regression coefficient, whichdescribes the unit change in f (x) (vertical axis values) per unit change in x(horizontal axis).For the selected area, Lin_reg computes the linear regression of the linedrawn as a best fit for all selected data points using the following formula:Lin_reg =n nWhere:n – number of samples;i – index (i = 1.n);x f x x f xi iii1 i1 i1nn22 n xi xii1i1nniVisit the online support center at www.biopac.com