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simple multiplication / summation using matlab

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Passband Modulation
i want to do some complicate calculations by matlab of following
n=0:65119;
x = cos(3.6*n)*sin(3.6*n);
y = x*x
it shows errors however, saying
Error in ==> ex3_1_2 at 3 x = cos(3.6*n)*sin(3.6*n);
what's happening?
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Passband Modulation
Passband Modulation 2012-10-4
that is a summation, summing up from n=0 to n=65119. as a result it must be 0:65119.

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Walter Roberson
Walter Roberson 2012-10-4
The MATLAB operator "*" is matrix multiplication. Element-by-element multiplication is ".*"
cos(3.6*n) .* sin(3.6*n)
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Passband Modulation
Passband Modulation 2012-10-4
is not the result of that mathematical equation a scalar/single number?? is not it a scalar summation?? or i just made wrong code that is a vector???
Walter Roberson
Walter Roberson 2012-10-4
You did not happen to show us the mathematical notation for what you are trying to do.
In MATLAB, 0:65119 is a row vector, 1 x 65120 in length. Matrix multiplication of two row vectors cannot be done: Matrix multiplication (mathematically) requires that the "inner dimensions" must be equal. Matrix multiplication is defined for (1 x 65120) * (65120 x 1) (giving a 1 x 1 result), and is defined for (65120 x 1) * (1 x 65120) (giving a 65120 x 65120 result), but it is not defined for (1 x 65120) * (1 x 65120)
It is mathematically possible to dot-product or cross-product vectors that have the same orientation; we cannot tell whether that is your intention.

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