Topic: DMD0121
Math Raise to a Power Operator
The Math Raise to a Power operator ( ** ) will calculate the result of a base raised to the power of an exponent. The result of this calculation will always be a Real (floating point) value and should be placed in a Real memory location to preserve the fractional portion. This is especially important if the exponent is negative or if the exponent is a Real value,
Any value raised to the 0 power is 1. The value 0 raised to any power is 0. Note: 0 raised to the 0 power is 1.
The base and exponent can be any mix of signed integers, unsigned integers, real (floating point) numbers or discrete values. They can be any numeric or discrete memory location or any numeric or discrete structure member.
Traditional math precedence rules are used to solve the math expression. The use of parentheses to remove any ambiguity in the processing order is encouraged.
Refer to the examples below:
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Signed Integers: assume D1 = 2 and D2 = 3
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D0 = D1 ** D2 |
D0 = 2 ** 3
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Both the base and the exponent are integer memory locations.
The result is placed in an integer memory location.
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D0 = (D1 ** D2) ** D1
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D0 = (2 ** 3) ** 2 D0 = 64
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The base and exponents are integer memory locations.
The result is placed in an integer memory location.
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D0 = D1 ** (D2 ** D1)
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D0 = 2 ** (3 ** 2) D0 = 512
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The base and exponents are integer memory locations.
The use of parentheses specifies the order of operation which yields a different result than the same values above.
The result is placed in an integer memory location.
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R0 = D1 ** 0.5 |
R0 = 2 ** 0.5 R0 = 1.414 |
The base is an integer memory locations, the exponent is a Real constant.
The exponent is non-integer, which will generate a non-integer result. Place the result in a Real memory location to preserve the fractional portion.
The result is placed in a Real memory location.
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R0 = D1 ** -3 |
R0 = 2 ** -3 R0 = 0.1250 |
The base is an integer memory locations, the exponent is an integer constant.
The exponent is negative, which will generate a non-integer result. Place the result in a Real memory location to preserve the fractional portion.
The result is placed in a Real memory location.
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Casting Numeric Values: assume DLV2000 and DLV2001 as a 32-bit Real = 123.45
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R0 = 123.45 ** 2 R0 = 15239.9
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The base is using the 'Real and DWord' cast operators, the exponent is an integer constant.
The result is placed in a floating point memory location.
DLV memory locations are 16-bit Unsigned used by external DirectLOGIC devices. In this example a remote DirectLOGIC CPU has written a 32-bit floating point value into two successive DLV memory locations. Using the :RD cast operator will interpret the 32-bit value in DLV2000 and DLV2001 as a REAL number.
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