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That expression is extremely difficult for a package to evaluate. We say it is ill conditioned. Adjust your digit command to get higher precision and try again.
]]>Ok.
For that expression I get:
-1.18059162071741e21
and 1.18059162071741e21 for those two numbers as integers.
With that identity as well as lots of others the best way is to plot (a+b)(a-b) - (a^2 - b^2 ). Instead of getting a flat line on the x axis ( y = 0 ) you should get a crazy graph of undulating spikes.
I meant the expression in post #1.
]]>Did you try that expression? What did you get?
Is it the identity you are asking about?
For numbers like a=1.1 and b=2.2, it displays correctly. When digits after decimal places are increased, it fails.
Did you try that expression? What did you get?
]]>For that identity, yes, real numbers are always a problem!
]]>There is a big difference between the way human mathematicians do math and the way a CAS does it. One of the funniest examples is
Human math: This is an identity:
Computer math: This is not!
]]>That is one of its problems. The guy who designed it wanted to prove there was a big hole in the way numerical people verify digits.
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