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49 lines
856 B
Text
49 lines
856 B
Text
// BigNumber test: calculate natural logarithm
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#include "BigNumber.h"
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BigNumber one (1);
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BigNumber two (2);
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BigNumber half ("0.5");
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BigNumber ln (BigNumber x)
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{
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// if x <= 0.5 or >= 2 take the square root and double the result
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if (x <= half || x >= two)
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{
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BigNumber e = ln (x.sqrt ());
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return e * two;
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} // end of x <= 0.5 or >= 2
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// some big numbers
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BigNumber a = (x - one) / (x + one);
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BigNumber e;
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BigNumber t = a;
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BigNumber i = one;
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BigNumber E;
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do
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{
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E = e;
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e += t / i;
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t *= a * a;
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i += two;
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} while (e != E);
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return e * two;
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} // end of function ln
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void setup ()
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{
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Serial.begin (115200);
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Serial.println ();
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Serial.println ();
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BigNumber::begin (45); // max around 45 on the Uno for ln (100)
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Serial.println (ln (100));
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} // end of setup
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void loop () { }
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