Friday, June 24, 2011
Practice for underflow and overflow in scientific notation.
Here is a link to a previous post about scientific notation, underflow and overflow.
Consider 80^80. If you enter this into your calculator, you will likely get an overflow error because the answer is more than 10^100. Here is how we can get around this, by splitting the number into two parts that are less than 10^100 and multiplying them together.
80^40 = 1.329227996 x 10^76
If we multiply 80^40 by 80^40, we will get 80^80. We need to square 1.329227996 to get the new significand, and the new exponent will be 10^(76+76) = 10^152
1.32922² = 1.766825808..., but since we only squared the number with six significant digits, we can only trust the answer to five significant digits, so our best answer is 1.7668 x 10^152.
More practice.
a) 40^80
b)40^-80
Answers in the comments.
Labels:
overflow,
practice problems,
scientific notation,
underflow
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1 comment:
a) 40^80
40^40 = 1.20882...x 10^64
1.20882² = 1.4612457..., but we can only rely on the first five digits, 1.4612
64+64 = 128
40^80 = 1.4612 x 10^128, to five significant digits.
b)40^-80
40^-40 = 8.271806...x10^-65
-65 + -65 = -130
8.271806² = 68.4227745, which is more than 10, so we change it to 6.8423 x 10^1
6.8423 x 10^1 x 10^-130 =
6.8423 x 10^-129, to five significant digits.
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