CMake/Tests/Tutorial/Step7/MathFunctions/mysqrt.cxx

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#include <stdio.h>
#include "MathFunctions.h"
#include "TutorialConfig.h"
// include the generated table
#include "Table.h"
#include <math.h>
// a hack square root calculation using simple operations
double mysqrt(double x)
{
if (x <= 0)
{
return 0;
}
double result;
// if we have both log and exp then use them
double delta;
// use the table to help find an initial value
result = x;
if (x >= 1 && x < 10)
{
result = sqrtTable[static_cast<int>(x)];
}
// do ten iterations
int i;
for (i = 0; i < 10; ++i)
{
if (result <= 0)
{
result = 0.1;
}
delta = x - (result*result);
result = result + 0.5*delta/result;
fprintf(stdout,"Computing sqrt of %g to be %g\n",x,result);
}
return result;
}