Numeric - Revision history

Logmanoriginal: /* Tips and tricks */ Add tip for arrow key navigation

2020-05-15T12:42:48Z

Tips and tricks: Add tip for arrow key navigation

← Older revision		Revision as of 12:42, 15 May 2020
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	== Tips and tricks ==		== Tips and tricks ==
			* Use the '''arrow''' keys to increment and decrement numeric controls and constants.

	===Advanced editing mode===		===Advanced editing mode===
	In the [[Numeric#property dialog\|Property dialog]], go to '''Display Format''' and select '''Advanced editing mode''' to specify the desired format string.		In the [[Numeric#property dialog\|Property dialog]], go to '''Display Format''' and select '''Advanced editing mode''' to specify the desired format string.

Logmanoriginal: Add tips and tricks

2020-05-15T12:40:43Z

Add tips and tricks

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 In summary, any binary representation will be approximate. How approximate is based on the word length. It is that factor of 5 in base 10 numbers that gets us. It appears that you have 17 digits of accuracy which is about right for a double precision number. Extended have more, singles have less. That is mathematical reality. Computers are not idealized mathematical machines. If it was easy everyone would be an expert. Knowing how things are treated by the underlying hardware can keep one from having these problems.
 [[Category:Numeric]]
 [[Category:Data types]]

Logmanoriginal: Mark for cleanup

2020-05-09T18:46:12Z

Mark for cleanup

← Older revision		Revision as of 18:46, 9 May 2020
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			{{cleanup}}
	== [[NaN]] equivalent for [[integer]] data types ==		== [[NaN]] equivalent for [[integer]] data types ==
	NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.		NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.

Logmanoriginal at 14:14, 19 July 2019

2019-07-19T14:14:26Z

← Older revision		Revision as of 14:14, 19 July 2019
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	In summary, any binary representation will be approximate. How approximate is based on the word length. It is that factor of 5 in base 10 numbers that gets us. It appears that you have 17 digits of accuracy which is about right for a double precision number. Extended have more, singles have less. That is mathematical reality. Computers are not idealized mathematical machines. If it was easy everyone would be an expert. Knowing how things are treated by the underlying hardware can keep one from having these problems.		In summary, any binary representation will be approximate. How approximate is based on the word length. It is that factor of 5 in base 10 numbers that gets us. It appears that you have 17 digits of accuracy which is about right for a double precision number. Extended have more, singles have less. That is mathematical reality. Computers are not idealized mathematical machines. If it was easy everyone would be an expert. Knowing how things are treated by the underlying hardware can keep one from having these problems.

	[[Category:~~numeric~~]]		[[Category:Numeric]]
			[[Category:Data types]]

Ackbeet: Spelling and Grammar

2007-12-26T12:49:02Z

Spelling and Grammar

← Older revision		Revision as of 12:49, 26 December 2007
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	== Comparing real numbers ==		== Comparing real numbers ==
	What you need is a comparison that assumes that equal is the same as close enough. One way is to define an epsilon and check to make sure that your error is greater than that epsilon where epsilon is dependent on the type of number (single, double, extended) that you are using. For example to compare A greater than or equal to B (as double precision) you could use as your test.		What you need is a comparison that assumes that equal is the same as close enough. One way is to define an epsilon and check to make sure that your error is greater than that epsilon where epsilon is dependent on the type of number (single, double, extended) that you are using. For example, to compare A greater than or equal to B (as double precision) you could use as your test the following:

	A-B >= -1e-17*(A+B)/2		A-B >= -1e-17*(A+B)/2

Tcplomp: GetMaxFromInf

2007-10-25T05:58:20Z

GetMaxFromInf

← Older revision		Revision as of 05:58, 25 October 2007
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	NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.		NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.

	'''A useful trick:''' In most cases, zero or -1 are used as the magic sentinel value for integer work. But sometimes you'd like to use "largest possible integer" as your sentinel value because zero and -1 are actual values, and you don't expect to ever actually use the large end of the spectrum. But nobody actually remembers the largest possible integer, and even if you look it up (it is in the Context Help for an integer wire, by the way), typing it is annoying. Solution: Drop a Numeric constant on the block diagram and set it to be your type of integer. Then type a long string of 9s into it, such as "99999999999999999999999999999999999999999". LabVIEW will automatically change this to be the largest possible integer storable in your data type. If it doesn't convert and you still have the long string of 9s, then you didn't type enough 9s. This can happen if you're using unsigned 64-bit integers... those things are HUGE!		'''A useful trick:''' In most cases, zero or -1 are used as the magic sentinel value for integer work. But sometimes you'd like to use "largest possible integer" as your sentinel value because zero and -1 are actual values, and you don't expect to ever actually use the large end of the spectrum. But nobody actually remembers the largest possible integer, and even if you look it up (it is in the Context Help for an integer wire, by the way), typing it is annoying. Solution:
			*Drop a Numeric constant on the block diagram and set it to be your type of integer. Then type a long string of 9s into it, such as "99999999999999999999999999999999999999999". LabVIEW will automatically change this to be the largest possible integer storable in your data type. If it doesn't convert and you still have the long string of 9s, then you didn't type enough 9s. This can happen if you're using unsigned 64-bit integers... those things are HUGE!
			*Another way to get the maximum value is the following snippet:
			[[Image:GetMax.png]]

	Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.		Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.

Smercer: /* NaN equivalent for integer data types */

2007-10-24T15:17:37Z

NaN equivalent for integer data types

← Older revision		Revision as of 15:17, 24 October 2007
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	NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.		NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.

	'''A useful trick:''' In most cases, zero or -1 are used as the magic sentinel value for integer work. But sometimes you'd like to use "largest possible integer" as your sentinel value because zero and -1 are actual values, and you don't expect to ever actually use the large end of the spectrum. But nobody actually remembers the largest possible integer, and even if you look it up (it is in the Context Help for an integer wire, by the way), typing it is annoying. Solution: Drop a Numeric constant on the block diagram and set it to be your type of integer. Then type a long string of 9s into it, such as "99999999999999999999999999999999999999999". LabVIEW will automatically change this to be the largest possible integer storable in your data type.		'''A useful trick:''' In most cases, zero or -1 are used as the magic sentinel value for integer work. But sometimes you'd like to use "largest possible integer" as your sentinel value because zero and -1 are actual values, and you don't expect to ever actually use the large end of the spectrum. But nobody actually remembers the largest possible integer, and even if you look it up (it is in the Context Help for an integer wire, by the way), typing it is annoying. Solution: Drop a Numeric constant on the block diagram and set it to be your type of integer. Then type a long string of 9s into it, such as "99999999999999999999999999999999999999999". LabVIEW will automatically change this to be the largest possible integer storable in your data type. If it doesn't convert and you still have the long string of 9s, then you didn't type enough 9s. This can happen if you're using unsigned 64-bit integers... those things are HUGE!

	Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.		Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.

Smercer: /* NaN equivalent for integer data types */

2007-10-24T15:08:58Z

NaN equivalent for integer data types

← Older revision		Revision as of 15:08, 24 October 2007
Line 2:		Line 2:
	NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.		NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.

	'''A useful trick:''' In most cases, zero or -1 are used as the magic sentinel value for integer work. But sometimes you'd like to use "largest possible integer" as your sentinel value because zero and -1 are actual values, and you don't expect to ever actually use the large end of the spectrum. But nobody actually remembers the largest possible integer, and even if you look it up, typing it is annoying. Solution: Drop a Numeric constant on the block diagram and set it to be your type of integer. Then type a long string of 9s into it, such as "99999999999999999999999999999999999999999". LabVIEW will automatically change this to be the largest possible integer storable in your data type.		'''A useful trick:''' In most cases, zero or -1 are used as the magic sentinel value for integer work. But sometimes you'd like to use "largest possible integer" as your sentinel value because zero and -1 are actual values, and you don't expect to ever actually use the large end of the spectrum. But nobody actually remembers the largest possible integer, and even if you look it up (it is in the Context Help for an integer wire, by the way), typing it is annoying. Solution: Drop a Numeric constant on the block diagram and set it to be your type of integer. Then type a long string of 9s into it, such as "99999999999999999999999999999999999999999". LabVIEW will automatically change this to be the largest possible integer storable in your data type.

	Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.		Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.

Smercer: /* NaN equivalent for integer data types */

2007-10-24T15:08:07Z

NaN equivalent for integer data types

← Older revision		Revision as of 15:08, 24 October 2007
Line 1:		Line 1:
	== [[NaN]] equivalent for [[integer]] data types ==		== [[NaN]] equivalent for [[integer]] data types ==
	NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.		NaN is defined only for floating point numbers. In a [[U32]] all the possible values are actual numbers and there is no place left for a special value that says there is nothing there. If you need an "empty" value in an integer data type you have to pick a value that never appears in your particular application (if there really is one) to serve as a flag. In other words there is no "empty value" in integer data types.

			'''A useful trick:''' In most cases, zero or -1 are used as the magic sentinel value for integer work. But sometimes you'd like to use "largest possible integer" as your sentinel value because zero and -1 are actual values, and you don't expect to ever actually use the large end of the spectrum. But nobody actually remembers the largest possible integer, and even if you look it up, typing it is annoying. Solution: Drop a Numeric constant on the block diagram and set it to be your type of integer. Then type a long string of 9s into it, such as "99999999999999999999999999999999999999999". LabVIEW will automatically change this to be the largest possible integer storable in your data type.

	Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.		Test a floating point wire for NaN by using [[Image:Nanfunc.png]] from the Comparison pallete.

Michael_Aivaliotis at 10:41, 8 October 2007

2007-10-08T10:41:14Z

← Older revision		Revision as of 10:41, 8 October 2007
Line 21:		Line 21:
	In summary, any binary representation will be approximate. How approximate is based on the word length. It is that factor of 5 in base 10 numbers that gets us. It appears that you have 17 digits of accuracy which is about right for a double precision number. Extended have more, singles have less. That is mathematical reality. Computers are not idealized mathematical machines. If it was easy everyone would be an expert. Knowing how things are treated by the underlying hardware can keep one from having these problems.		In summary, any binary representation will be approximate. How approximate is based on the word length. It is that factor of 5 in base 10 numbers that gets us. It appears that you have 17 digits of accuracy which is about right for a double precision number. Extended have more, singles have less. That is mathematical reality. Computers are not idealized mathematical machines. If it was easy everyone would be an expert. Knowing how things are treated by the underlying hardware can keep one from having these problems.

	[[Category:~~Data types~~]]		[[Category:numeric]]