27 lines
832 B
Markdown
27 lines
832 B
Markdown
A short look to [Wikipedia](https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Digit-by-digit_calculation) finds us a neat algorithm to calculate the square-root digit-by-digit.
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I have optimized it a little bit with the target to use not so many variables:
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~~~
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IEnumerable<int> DRoot(int r)
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{
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BigInteger c = r;
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BigInteger p = 0;
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int x = 0;
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for (ii = 0; ii < 100; ii++)
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{
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for (x = 0;(x+1)*(20*p + (x+1)) <= c;x++);
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c = 100*c - 2000*p*x - 100*x*x;
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p = p*10 + x;
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}
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return p;
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}
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~~~
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The algorithm is pretty simple, but *god* do I hate long addition/multiplication in Befunge.
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We need 120 base-10 digits for the numbers `p`and `c`.
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In our program we use base-100 notation. This way we can fit the numbers in a single befunge-93 row
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**and** can simply multiply by 100 with a single left shift operation. |