MHB Find Relative Error of A: 2.33

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The discussion focuses on calculating the relative error of the expression A = (317 + 0.3) - (171.499 + 145.501) with a base of 10 and a precision of 3. The initial calculation resulted in a relative error of 2.33, derived from the formula ||A - fl(A)|| / ||A||. However, it was later clarified that the correct calculation should use the values A = 0.3 and fl(A) = 1, leading to a relative error of 2.33 as well, but the user initially misstated the fraction as 7/5 instead of the correct 7/3. The final confirmation indicates that the calculations align, but the user acknowledges the error in notation. The discussion concludes with a resolution of the confusion regarding the relative error calculation.
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Hey! :rolleyes: I have also an other question :o
Suppose the base $\beta =10$ ,the precision $t=3$, $-L=U=10$ and $$A=(317+0.3)-(171.499+145.501)$$
I have to find the relative error for $A$.
We don't make rounding.For example,if we have the value $345.924$ it is equal to $0.345924*10^3$ and the corresponding floating number is $0.345*10^3$.
I found that it is equal to
$$\frac{||A-fl(A)||}{||A||}=\frac{7}{5}=2.33$$
Could you tell me if it is right?
 
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evinda said:
Hey! :rolleyes: I have also an other question :o
Suppose the base $\beta =10$ ,the precision $t=3$, $-L=U=10$ and $$A=(317+0.3)-(171.499+145.501)$$
I have to find the relative error for $A$.
We don't make rounding.For example,if we have the value $345.924$ it is equal to $0.345924*10^3$ and the corresponding floating number is $0.345*10^3$.
I found that it is equal to
$$\frac{||A-fl(A)||}{||A||}=\frac{7}{5}=2.33$$
Could you tell me if it is right?

I found that A=0.3 and fl(A)=1..
 
evinda said:
I found that A=0.3 and fl(A)=1..

Looks good! ;)... but doesn't that mean that:
$$\frac{||A-fl(A)||}{||A||} = \frac{|0.3 - 1|}{|0.3|} = \frac{0.7}{0.3} = 2.33$$

Oh wait! You also got $2.33$... while you shouldn't have. :eek: :rolleyes:
 
I like Serena said:
Looks good! ;)... but doesn't that mean that:
$$\frac{||A-fl(A)||}{||A||} = \frac{|0.3 - 1|}{|0.3|} = \frac{0.7}{0.3} = 2.33$$

Oh wait! You also got $2.33$... while you shouldn't have. :eek: :rolleyes:

I accidentally wrote $\frac{7}{5}$ :o I meant that it is equal to $\frac{7}{3}$..

Thank you very much! (Mmm)
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...

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