CHECK_MATH Function

Returns and clears the accumulated math error status.

CAUTION: On machines that do not implement the IEEE standard for floating-point math, CHECK_MATH does not properly maintain an accumulated error status.

Keywords

Trap Controls how floating-point traps are handled:

If set to 0, no error messages are printed except the final accumulated error status.
If set to 1 (the default), traps are enabled and programs are allowed to continue after floating-point errors. The first eight floating-point error exceptions issue messages. Subsequent errors are silent.

If a floating-point error occurs which is not logged, the accumulated floating-point error status is printed when PV-WAVE returns to the interactive mode.

NOTE: Trap handling is machine dependent. Some machines won't work properly with traps enabled, while others don't allow disabling traps.

Discussion

The result of CHECK_MATH is 0 if no math errors have occurred since the last call or issuance of the interactive prompt. Other error status values as follows, where each binary bit represents an error:


Value	Condition
0	No errors detected since the last interactive prompt or call to CHECK_MATH.
1	Integer divide by zero.
2	Integer overflow.
16	Floating-point divide by zero.
32	Floating-point underflow.
64	Floating-point overflow.
128	Floating-point operand error. An illegal operand was encountered, such as a negative operand to the SQRT or ALOG functions; or an attempt to convert to integer a number whose absolute value is greater than 2³¹ - 1.

CAUTION: Not all machines detect all errors.

Example

a = [1.0, 1.0, 2.0]

; Array a will not fail as divisor.

b = [1.0, 0.0, 2.0]

; The second element in array b should cause a divide-by-zero error.

junkstatus = CHECK_MATH(1, 0, Trap=1)

; Clear the previous error status and print error messages if an error exists.

c = 1.0 / a
status = CHECK_MATH(0, 0)
PRINT, a, c, status

1.00000      1.00000      2.00000
1.00000      1.00000     0.500000
            0

d = 1.0 / b

; Cause an integer divide-by-zero error.

% Program caused arithmetic error: 
% Floating divide by 0
% Detected at $MAIN$ .

status = CHECK_MATH(0, 0)
PRINT, b, d, status

1.00000      0.00000      2.00000
1.00000          Inf     0.500000
          16

CHECK_MATH Function

Usage

Input Parameters

Returned Value

Keywords

Discussion

Example

See Also