Graphics Programs Reference

In-Depth Information

>> whos

Name

Size

Bytes Class

data

128x103x9

949248 double array

f

1x103824 double array

t

1x9

72 double array

th

1x128

1024 double array

The data consists of spectra measured at 103 frequencies, 128 arrival

angles, and 9 time steps. Let us plot the fifth time sample:

colormap(flipud(gray))

imagesc(f,th,data(:,:,5))

axis xy

colorbar

xlabel('Frequency, Hz')

ylabel('Arrival angle, degrees')

Darker colours correspond to higher intensities. You can see two strong

sources at an angle of zero degrees and at frequencies of 85 and 170 Hz.

The fact that 170 = 2

85 might lead us to suspect that the 170 Hz

source is just the first harmonic of the 85 Hz source. Let us look at all of

the time samples together. This time we'll cut off the lower intensities

by setting the minimum colour to correspond to an intensity of 5 (this

is the call to
caxis
in the following code). We also turn off the
y
-axis

tick labels for all but the first plot, and we make the tick marks point

outwards:
10

×

for i = 1:9

subplot(3,9,i), imagesc(f,th,data(:,:,i)), axis xy

set(gca,'tickdir','out')

ifi==1

ylabel('Arrival angle, degrees')

xlabel('Frequency, Hz')

end

if i>1, set(gca,'yticklabel',[]), end

caxis([5 Inf]), title(['i_t = ' num2str(t(i))])

end

10
See Handle Graphics Sections 23 and 31 (pages 63 and 107).