purpose of a period in a var set/equation ?

from

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fsamp = 11025;

dt = 1/fsamp;

dur = 1.8;

tt = 0 : dt : dur;

psi = 2*pi*(100 + 200*tt + 500*tt.*tt);

xx = real( 7.7*exp(j*psi) );

soundsc( xx, fsamp )

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what is the purpose of the period in "psi = 2*pi*(100 + 200*tt + 500*tt.*tt)" ?

Answer 1

[Andrew Newell]

With the dot, it indicates element-by-element multiplication instead of matrix multiplication. See Matrix and array arithmetic.