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•Division by zero—The divisor is zero, and the dividend is a finite non-zero number; or, more generally, an exact infinite result is delivered by an operation on finite operands.

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Overflow—The correctly rounded result is larger than the largest number in the required precision.

Underflow—The number is too small, or precision is lost, and no signal handler is established for underflow.

•Inexact—The rounded result of a valid operation is different from the infinitely precise result. This exception occurs whenever there is untrapped overflow or untrapped underflow.

Math Library Exception-Handling Function: matherr()

Some libm functions are specified to call matherr()when an exception is detected. You can redefine matherr() by including a function named matherr() in the program. When an exception occurs, a pointer to the exception structure, exc, is passed to the user-supplied matherr() function. This structure, defined in the math_p.h header file, is as follows:

type

exception = record

kind: integer;

name: ^string;

arg1: double;

arg2: double;

retval: double; end;

The element kind is an integer constant that describes the type of exception that occurred, and is one of the following constants. These constants are defined in the header file.

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Pascal 4.0 User’s Guide