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df9cdf629c
* Updated output message * Use 'target_compile_definitions' for HAVE_LOG and HAVE_EXP Previously, the change from using TutorialConfig.h to target_compile_definitions happened without explanation as part of Step 8.
46 lines
1.0 KiB
C++
46 lines
1.0 KiB
C++
#include "MathFunctions.h"
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#include <iostream>
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// include the generated table
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#include "Table.h"
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#include <cmath>
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namespace mathfunctions {
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namespace detail {
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// a hack square root calculation using simple operations
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double mysqrt(double x)
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{
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if (x <= 0) {
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return 0;
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}
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// if we have both log and exp then use them
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#if defined(HAVE_LOG) && defined(HAVE_EXP)
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double result = exp(log(x) * 0.5);
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std::cout << "Computing sqrt of " << x << " to be " << result
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<< " using log and exp" << std::endl;
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#else
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// use the table to help find an initial value
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double result = x;
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if (x >= 1 && x < 10) {
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result = sqrtTable[static_cast<int>(x)];
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}
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// if we have both log and exp then use them
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// do ten iterations
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for (int i = 0; i < 10; ++i) {
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if (result <= 0) {
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result = 0.1;
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}
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double delta = x - (result * result);
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result = result + 0.5 * delta / result;
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std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
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}
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#endif
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return result;
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}
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}
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}
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