Microsoft KB Archive/57918

= Handling Floating-Point Exceptions in FORTRAN =

Article ID: 57918

Article Last Modified on 12/1/2003

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APPLIES TO


 * Microsoft FORTRAN Compiler 3.3
 * Microsoft FORTRAN Compiler 3.31
 * Microsoft FORTRAN Compiler 4.0
 * Microsoft FORTRAN Compiler 4.01
 * Microsoft FORTRAN Compiler 4.1
 * Microsoft FORTRAN Compiler 5.0
 * Microsoft FORTRAN Compiler 5.1
 * Microsoft FORTRAN Compiler 4.1
 * Microsoft FORTRAN Compiler 5.0
 * Microsoft FORTRAN Compiler 5.1
 * Microsoft FORTRAN PowerStation 1.0 Standard Edition
 * Microsoft Fortran PowerStation 1.0a for MS-DOS
 * Microsoft FORTRAN PowerStation 32
 * Microsoft FORTRAN PowerStation 32

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This article was previously published under Q57918



SUMMARY
The IEEE floating point standard defines the following five exceptions: invalid operation, divide by zero, overflow, underflow, and precision. The Microsoft FORTRAN run-time libraries provide the following three routines to obtain and modify the value of the status and control words:


 * The store-status-word (SSWRQQ) function returns the value of the status word.
 * The store-control-word (SCWRQQ) function returns the value of the control word.
 * The load-control-word (LCWRQQ) function sets the control word to a specified value.

An application can specify the manner to handle an exception by changing the control word and can determine which exceptions have occurred by checking the value of the status word.



MORE INFORMATION
The following code example demonstrates using the LCWRQQ function to disable the overflow and divide by zero exceptions and their corresponding run-time errors.

Sample Code
C Compile options needed: None

INTERFACE TO SUBROUTINE LCWRQQ(CW) INTEGER*2 CW     END

PROGRAM NOEXCEPTIONS

INTEGER*2 CW     PARAMETER(CW = 16#133F) REAL*4 X, Y, Z

X = 1.0 Y = 0.0

CALL LCWRQQ(CW)

Z = X / Y

END NOTE: In FORTRAN PowerStation, GETSTATUSFPQQ is equivalent to SSWRQQ, GETCONTROLFPQQ is equivalent to SCWRQQ, and SETCONTROLFPQQ is equivalent to LCWRQQ.

Additional query words: kbinf 1.00 3.30 4.00 4.10 5.00 5.10

Keywords: kblangfortran KB57918

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