why does Matlab not expand(abs(a-b)^2) ?

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Niklas Kurz
Niklas Kurz 2020-10-14
编辑： Niklas Kurz 2020-10-18
Wolfram alpha shows: a^2 -2*a*b+b^2

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Walter Roberson
Walter Roberson 2020-10-14
>> a=complex(rand,rand)
a =
0.0975404049994095 + 0.278498218867048i
>> b=complex(rand,rand)
b =
0.546881519204984 + 0.957506835434298i
>> abs(a-b)^2
ans =
0.662960138288077
>> a^2-2*a*b+b^2
ans =
-0.259145264457063 + 0.610212976647027i
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Niklas Kurz
Niklas Kurz 2020-10-18
编辑：Niklas Kurz 2020-10-18
Hence it's incorrect for complex numbers. Alrigth. But for real numbers it should work. However
expand(abs(real(a)-real(b))^2
still doesn't expand.

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