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-rw-r--r--Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx17
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;
}