Data Type Troubleshooting

What follows is a list of problems that can occur when you use intrinsic data types.

Floating-point values do not compare as equal

When you use floating-point numbers (Real32, Real64, and Real128), know that they are stored as binary fractions. They can hold an accurate quantity only when it is a binary fraction with k / (2 ^ n), where k and n are integers. For example, 0.5 = 1/2 and 0.1875 = 3/16. Thus these are accurate values. But 0.3 = 3/10 and 0.15 = 3/20, thus these are approximate values.

Because of this, you cannot be sure of accurate values as a result of floating-point operations. Thus you must not think that two given values will be equal only because mathematics tells you that they are.

To compare floating-point values, follow these steps:

• Select a satisfactory maximum tolerance for the given comparison. All values in this range will become equal.
• Put Tol directly after the end of the comparison expression.
• Follow that with the selected tolerance value. This can be a floating-point literal or a declared constant (See Const).

See Tol Clause for more information.

Boolean to numeric type conversion causes problems

TODO

See also

• Type Conversions