specbandwidth

The specbandwidth function determines the bandwidth of a narrowband spectral power distributions (SPDs) at one half peak maximum or other thresholds.

Usage:

[sbw,lam1,lam2] = specbandwidth(lam,spec,threshold,method)

Where:

Parameter	Description
sbw	Is the returned spectral bandwidth
lam1	Returns the left side of the spectral bandwidth
lam2	Returns the right side of the spectral bandwidth
lam	Is the input vector or matrix containing the wavelengths, row-wise
spec	Is the input vector or matrix containing the spectral power distribution, row-wise
threshold	Defines at which percentage of the peak at which the bandwidth is to be determined, default: 50.
method	Defines the interpolation method, used to determine the wavelengths: ‘linear’: Linear interpolation from nearest neighbours (default) ‘pchip’: Piecewise cubic Hermite interpolating polynomial—shape-preserving interpolation with smooth first derivative ‘cubic’: Cubic spline interpolation—smooth first and second derivatives throughout the curve

Examples

Determine the spectral bandwidth of the V(\lambda) curve:

lam = 380:780;
VL = ciespec(lam,'VL');
sbw = specbandwidth(lam,VL)

See also: ciespec

Result:

swb = 100.39

Plot the spectral bandwidth for V(\lambda) at 75% peak height:

lam = 380:780;
VL = ciespec(lam,'VL');
threshold = 75;
[sbw,lam1,lam2] = specbandwidth(lam,VL,threshold);

% plotting
plot(lam,VL)
hold on
grid minor
plot([lam1 lam1 lam2 lam2],[0 threshold threshold 0]./100,'--k')
text(lam1+(lam2-lam1)/2,(threshold+5)./100,['bw = ',num2str(sbw),' nm'])
xlabel('$\lambda$ in nm')
ylabel('relative SPD')
hold off
texify

See also: ciespec, texify

Result:

Determine the spectral bandwidth of the α-opic functions:

lam = 380:780;
spec = ciespec(lam,'aopic');
sbw = specbandwidth(lam,spec)

See also: ciespec

Result:

sbw = 52.709    93.698   113.072    94.990    84.439

Determine the spectral bandwidth of the α-opic functions using ‘pchip’ interpolation:

lam = 380:780;
spec = ciespec(lam,'aopic');
sbw = specbandwidth(lam,spec,50,'pchip')

See also: ciespec

Result:

sbw = 52.711    93.696   113.071    94.991    84.436

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