diff options
Diffstat (limited to 'Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx')
-rw-r--r-- | Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx index 7d80ee9648..7eecd26b5d 100644 --- a/Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx +++ b/Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx @@ -1,10 +1,8 @@ +#include <cmath> #include <iostream> #include "MathFunctions.h" -// include the generated table -#include "Table.h" - // a hack square root calculation using simple operations double mysqrt(double x) { @@ -12,12 +10,13 @@ double mysqrt(double x) return 0; } - // use the table to help find an initial value + // if we have both log and exp then use them +#if defined(HAVE_LOG) && defined(HAVE_EXP) + double result = std::exp(std::log(x) * 0.5); + std::cout << "Computing sqrt of " << x << " to be " << result + << " using log and exp" << std::endl; +#else double result = x; - if (x >= 1 && x < 10) { - std::cout << "Use the table to help find an initial value " << std::endl; - result = sqrtTable[static_cast<int>(x)]; - } // do ten iterations for (int i = 0; i < 10; ++i) { @@ -28,6 +27,6 @@ double mysqrt(double x) result = result + 0.5 * delta / result; std::cout << "Computing sqrt of " << x << " to be " << result << std::endl; } - +#endif return result; } |