From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/c/numeric%2Fmath%2Fscalbn.html | 99 ++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 devdocs/c/numeric%2Fmath%2Fscalbn.html (limited to 'devdocs/c/numeric%2Fmath%2Fscalbn.html') diff --git a/devdocs/c/numeric%2Fmath%2Fscalbn.html b/devdocs/c/numeric%2Fmath%2Fscalbn.html new file mode 100644 index 00000000..0a6b35c7 --- /dev/null +++ b/devdocs/c/numeric%2Fmath%2Fscalbn.html @@ -0,0 +1,99 @@ +

scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl

Defined in header <math.h> 
float       scalbnf( float arg, int exp );
+		 (1) (since C99) 
double      scalbn( double arg, int exp );
+		 (2) (since C99) 
long double scalbnl( long double arg, int exp );
+		 (3) (since C99)
Defined in header <tgmath.h> 
#define scalbn( arg, exp )
+		 (4) (since C99)
Defined in header <math.h> 
float       scalblnf( float arg, long exp );
+		 (5) (since C99) 
double      scalbln( double arg, long exp );
+		 (6) (since C99) 
long double scalblnl( long double arg, long exp );
+		 (7) (since C99)
Defined in header <tgmath.h> 
#define scalbln( arg, exp )
+		 (8) (since C99)
+1-3,5-7) Multiplies a floating point value arg by FLT_RADIX raised to power exp.
+4,8) Type-generic macros: If arg has type long double, scalbnl or scalblnl is called. Otherwise, if arg has integer type or the type double, scalbn or scalbln is called. Otherwise, scalbnf or scalblnf is called, respectively.

Parameters

+ + +
arg - floating point value
exp - integer value

Return value

If no errors occur, arg multiplied by FLT_RADIX to the power of exp (arg×FLT_RADIXexp) is returned.

+

If a range error due to overflow occurs, ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL is returned.

+

If a range error due to underflow occurs, the correct result (after rounding) is returned.

+

Error handling

Errors are reported as specified in math_errhandling.

+

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

+

Notes

On binary systems (where FLT_RADIX is 2), scalbn is equivalent to ldexp.

+

Although scalbn and scalbln are specified to perform the operation efficiently, on many implementations they are less efficient than multiplication or division by a power of two using arithmetic operators.

+

The scalbln function is provided because the factor required to scale from the smallest positive floating-point value to the largest finite one may be greater than 32767, the standard-guaranteed INT_MAX. In particular, for the 80-bit long double, the factor is 32828.

+

Example

#include <errno.h>
+#include <fenv.h>
+#include <float.h>
+#include <math.h>
+#include <stdio.h>
+ 
+// #pragma STDC FENV_ACCESS ON
+ 
+int main(void)
+{
+    printf("scalbn(7, -4) = %f\n", scalbn(7, -4));
+    printf("scalbn(1, -1074) = %g (minimum positive subnormal double)\n",
+            scalbn(1, -1074));
+    printf("scalbn(nextafter(1,0), 1024) = %g (largest finite double)\n",
+            scalbn(nextafter(1,0), 1024));
+ 
+    // special values
+    printf("scalbn(-0, 10) = %f\n", scalbn(-0.0, 10));
+    printf("scalbn(-Inf, -1) = %f\n", scalbn(-INFINITY, -1));
+ 
+    // error handling
+    errno = 0; feclearexcept(FE_ALL_EXCEPT);
+    printf("scalbn(1, 1024) = %f\n", scalbn(1, 1024));
+    if (errno == ERANGE)
+        perror("    errno == ERANGE");
+    if (fetestexcept(FE_OVERFLOW))
+        puts("    FE_OVERFLOW raised");
+}

Possible output:

+
scalbn(7, -4) = 0.437500
+scalbn(1, -1074) = 4.94066e-324 (minimum positive subnormal double)
+scalbn(nextafter(1,0), 1024) = 1.79769e+308 (largest finite double)
+scalbn(-0, 10) = -0.000000
+scalbn(-Inf, -1) = -inf
+scalbn(1, 1024) = inf
+    errno == ERANGE: Numerical result out of range
+    FE_OVERFLOW raised

References

See also

+ + +
+
(C99)(C99)
 breaks a number into significand and a power of 2
(function)
+
(C99)(C99)
 multiplies a number by 2 raised to a power
(function)
C++ documentation for scalbn
+

+ © cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
+ https://en.cppreference.com/w/c/numeric/math/scalbn +

+
-- cgit v1.2.3