Purpose
Returns the absolute value of A times the sign of B. If A is non-zero, you can use the result to determine whether B is negative or non-negative, as the sign of the result is the same as the sign of B.
Note that if you have declared B as REAL(4) or REAL(8), and B has a negative zero value, the sign of the result depends on whether you have specified the -qxlf90=signedzero compiler option.
Class
Elemental function
Argument type and attributes
- A
- must be of type integer or real.
- B
- must be of the same type and kind type parameter as A.
Result type and attributes
Same as A.
Result value
- sgn = -1, if either of the following
is true:
- B < 0
B
is a REAL(4) or REAL(8) number
with a value of negative 0, and you have specified the -qxlf90=signedzero option 
- sgn = 1, otherwise.
Fortran 95 allows a processor to distinguish between a positive and a negative real zero, whereas Fortran 90 did not. Using the -qxlf90=signedzero option allows you to specify the Fortran 95 behavior (except in the case of REAL(16) numbers), which is consistent with the IEEE standard for binary floating-point arithmetic. -qxlf90=signedzero is the default for the bgxlf95, bgxlf95_r, bgf2003, and bgf2008 invocation commands.
Examples
SIGN (-3.0, 2.0) has the value 3.0.
| Specific Name | Argument Type | Result Type | Pass As Arg? |
|---|---|---|---|
| SIGN | default real | default real | yes |
| ISIGN | any integer 1 | same as argument | yes |
| DSIGN | double precision real | double precision real | yes |
| QSIGN | REAL(16) | REAL(16) | yes 2 |
Note:
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Related information
See -qxlf90 in the XL Fortran Compiler Reference.