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c++ - sqrt() error

reply "Jim Jennings" <jwjenn mindspring.com> writes:
todouble() converts two ints, a numerator and a denominator, into a double
and returns it. When I try to take the square root of the double, I get the
errors below. As hard as it is to believe STLport will only take the square
root of a float and a long double. (See _cmath.h, which is included in
cmath.) When I cast the return of todouble() to long double it worked.

        std::cout << "Fraction x is " << x << "\tsqrt x is "<<
std::sqrt(x.todouble()) << std::endl;
                                 ^
ftest6.cpp(40) : Error: ambiguous reference to symbol
Had: std::_inline_sqrt(float )
and: std::_inline_sqrt(long double )
frac6WR.cpp:
ftest6.cpp:
--- errorlevel 1
Mar 18 2003
parent reply "Nic Tiger" <nictiger progtech.ru> writes:
Some of math functions, and sqrt among them, are #define'd in math.h.
Defines serve to promote sqrt/sin/cos an other calls to intrinsic calls. But
this surely prevents normal usage of STL.

When ported Blitz to DMC++, I used the code below to suppress this errors:
-----------
#include <math.h>
#undef sin
#undef cos
#undef fabs
#undef sqrt

inline double cos (double x) { return _inline_cos(x);}
inline double sin (double x) { return _inline_sin(x);}
inline double fabs (double x) { return _inline_fabs(x);}
inline double sqrt (double x) { return _inline_sqrt(x);}
------------
You should insert it before you make calls to std::sqrt.

Or even simpler solution, write sqrt instead of std::sqrt.

Nic Tiger.

"Jim Jennings" <jwjenn mindspring.com> сообщил/сообщила в новостях
следующее: news:b57s60$16lp$1 digitaldaemon.com...
 todouble() converts two ints, a numerator and a denominator, into a double
 and returns it. When I try to take the square root of the double, I get

 errors below. As hard as it is to believe STLport will only take the

 root of a float and a long double. (See _cmath.h, which is included in
 cmath.) When I cast the return of todouble() to long double it worked.

         std::cout << "Fraction x is " << x << "\tsqrt x is "<<
 std::sqrt(x.todouble()) << std::endl;
                                  ^
 ftest6.cpp(40) : Error: ambiguous reference to symbol
 Had: std::_inline_sqrt(float )
 and: std::_inline_sqrt(long double )
 frac6WR.cpp:
 ftest6.cpp:
 --- errorlevel 1

Mar 18 2003
parent "Jim Jennings" <jwjenn mindspring.com> writes:
Thank you, Nic.
This works. I have filed this away, and will use it in the future.
JIm

"Nic Tiger" <nictiger progtech.ru> wrote in message
news:b588j0$1gpb$1 digitaldaemon.com...
 Some of math functions, and sqrt among them, are #define'd in math.h.
 Defines serve to promote sqrt/sin/cos an other calls to intrinsic calls.

 this surely prevents normal usage of STL.

 When ported Blitz to DMC++, I used the code below to suppress this errors:
 -----------
 #include <math.h>
 #undef sin
 #undef cos
 #undef fabs
 #undef sqrt

 inline double cos (double x) { return _inline_cos(x);}
 inline double sin (double x) { return _inline_sin(x);}
 inline double fabs (double x) { return _inline_fabs(x);}
 inline double sqrt (double x) { return _inline_sqrt(x);}
 ------------
 You should insert it before you make calls to std::sqrt.

 Or even simpler solution, write sqrt instead of std::sqrt.

 Nic Tiger.

Mar 18 2003