if within while loop not recognized

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Ramu Nair R
Ramu Nair R 2018-4-2
编辑： Ramu Nair R 2018-4-2
while(t<0.1)
if(t==0.05) v=3; end % NOT GETTING REFLECTED IN v
t=t+Ts;
end

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Birdman
Birdman 2018-4-2
编辑：Birdman 2018-4-2
A trivial answer:
Use ismembertol for comparing values with tolerance
tol=1e-6;
if ismembertol(t,0.05,tol)

更多回答（1 个）

John D'Errico
John D'Errico 2018-4-2
NEVER test for exact equality of a floating point number.
Since doubles are stored in binary, remember that almost all decimal fractions cannot be represented exactly as a double, just like you cannot represent 1/3 exactly as a terminating decimal in a limited number of decimal digits. Doubles use 52 binary bits to store the mantissa, so that is your limit.
Instead, 0.05 is stored as the closest value possible. So never test for exact equality. Just use a tolerance.
if abs(t - 0.05) < 1e-16

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