System Variable PP: Difference between revisions

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<h1>{quad}PP - Print Precision</h1>
<h1><aplxx>⎕PP</aplxx> - Print Precision</h1>
{{BoxStart|⎕PP
{{BoxStart|⎕PP
| Print Precision}}
| Print Precision}}
{{BoxEnd|⎕PP←'<i>VALUE</i>'}}
{{BoxEnd|⎕PP←'<i>VALUE</i>'}}


System Variable '''⎕PP''' or '''Quad PP''' refers to Print Precision.
System Variable <apll>⎕PP</apll> refers to Print Precision.
In NARS, the default Print Precision is:
In NARS2000, the default Print Precision is:
<pre>
 
<apll><pre>
       ⎕PP
       ⎕PP
10
10
Line 15: Line 16:
       ⍴⍕1÷3
       ⍴⍕1÷3
12            ⍝ 10 significant digits after the decimal point, plus 0 and decimal point itself = 12 chars (shape)
12            ⍝ 10 significant digits after the decimal point, plus 0 and decimal point itself = 12 chars (shape)
</pre>
Although 10 significant digits represent the print precision or displayed precision - actual computer stored formats are quite different.  Historically or customarily, ⎕PP is normally assigned a value of between 1 and 16, although with 64-bit systems, higher print precision values are available.  As an example, pollution is frequently cited in PPM's or parts per million or say 1 in 1,000,000 so 5-signficant digits in the data plus 7 digits within a million base might mean ⎕PP should be set as 5+7 = 12 significant digits, or greater for higher precision printed reports.  Note that print precision does NOT normally affect stored/digitized numbers, unless the numbers were first formatted/printed, then re-executed into digital floating point numbers.


See also '''[[System_Function_DR|System Function ⎕DR]]'''.<br>
      X←1÷3
      X
0.3333333333
      ⎕PP←4    ⍝ print precision changed to 4 digits
      X
0.3333
      X←⍎⍕X    ⍝ X is now formatted(printed) and re-executed into a number (for demonstration purposes only, AVOID in practice!!!)
      X
0.3333
      ⎕PP←10  ⍝ print precision is restored to 10 digits
      X
0.3333        ⍝ but X now only has 4 significant digits in it, as a result of ⎕PP reduction, formatting and re-execution into a number.
</pre></apll>
 
Although 10 significant digits represent the print precision or displayed precision, actual computer stored formats are quite different.  Historically or customarily, <apll>⎕PP</apll> is normally assigned a value of between 1 and 16, although with [[Rational_and_VFP_Numbers|Multiple-precision Floating Point numbers]], higher print precision values may be needed.  As an example, pollution is frequently cited in PPM's or parts per million or say 1 in 1,000,000 so 5-signficant digits in the data plus 7 digits within a million base might mean <apll>⎕PP</apll> should be set as 5+7 = 12 significant digits, or greater for higher precision printed reports.  Note that print precision does NOT affect stored/digitized numbers, '''unless''' the numbers were first formatted/printed, then re-executed into digital floating point numbers as the above example shows.
 
See also '''[[System_Function_DR|System Function ⎕DR]]'''.
 
{{System Variables}}
{{System Variables}}
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Latest revision as of 12:00, 16 April 2018

⎕PP - Print Precision

⎕PP Print Precision
⎕PP←'VALUE'

System Variable ⎕PP refers to Print Precision. In NARS2000, the default Print Precision is: 

      ⎕PP
10
      1÷3
0.3333333333   ⍝ 10 significant digits after the decimal point are shown
      ⍕1÷3
0.3333333333   ⍝ 10 significant digits after the decimal point are shown, for formatted result
      ⍴⍕1÷3
12             ⍝ 10 significant digits after the decimal point, plus 0 and decimal point itself = 12 chars (shape)

      X←1÷3
      X
0.3333333333
      ⎕PP←4    ⍝ print precision changed to 4 digits
      X
0.3333
      X←⍎⍕X    ⍝ X is now formatted(printed) and re-executed into a number (for demonstration purposes only, AVOID in practice!!!)
      X
0.3333
      ⎕PP←10   ⍝ print precision is restored to 10 digits
      X
0.3333         ⍝ but X now only has 4 significant digits in it, as a result of ⎕PP reduction, formatting and re-execution into a number.

Although 10 significant digits represent the print precision or displayed precision, actual computer stored formats are quite different. Historically or customarily, ⎕PP is normally assigned a value of between 1 and 16, although with Multiple-precision Floating Point numbers, higher print precision values may be needed. As an example, pollution is frequently cited in PPM's or parts per million or say 1 in 1,000,000 so 5-signficant digits in the data plus 7 digits within a million base might mean ⎕PP should be set as 5+7 = 12 significant digits, or greater for higher precision printed reports. Note that print precision does NOT affect stored/digitized numbers, unless the numbers were first formatted/printed, then re-executed into digital floating point numbers as the above example shows.

See also System Function ⎕DR.

System Variables (A value may be assigned to these except for ⎕DM)
⎕ALX ⎕CT ⎕DM ⎕DT ⎕ELX ⎕FC ⎕FEATURE ⎕FPC ⎕IC ⎕IO
⎕LR ⎕LX ⎕PP ⎕PR ⎕PW ⎕RL ⎕SA ⎕WSID
Niladic System Functions (a value cannot be assigned to these)
⎕A ⎕AV ⎕EM ⎕ET ⎕LC ⎕NNAMES ⎕NNUMS ⎕SI ⎕SYSID ⎕SYSVER
⎕T ⎕TC ⎕TCBEL ⎕TCBS ⎕TCESC ⎕TCFF ⎕TCHT ⎕TCLF ⎕TCNL ⎕TCNUL
⎕TS ⎕WA
Monadic or dyadic system functions (a value cannot be assigned to these)
⎕AT ⎕CR ⎕DC ⎕DFT ⎕DL ⎕DR ⎕EA ⎕EC ⎕ERROR ⎕ES
⎕EX ⎕FMT ⎕FX ⎕MF ⎕NAPPEND ⎕NC ⎕NCREATE ⎕NERASE ⎕NINFO ⎕NL
⎕NLOCK ⎕NREAD ⎕NRENAME ⎕NREPLACE ⎕NRESIZE ⎕NSIZE ⎕NTIE ⎕NUNTIE ⎕STOP ⎕TF
⎕TRACE ⎕UCS ⎕VR
Note that quad functions and variables (except for the ⎕A family of functions) are case insensitive


See Also
System Commands System Variables and Functions Operators


Keyboard
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Alt ? ⍵ ∊ ⍴ § ↑ ↓ ⍳ ○ π ← → ⊢
Shift Q W E R T Y U I O P { } |
Key q w e r t y u i o p [ ] \
Alt+Shift ∫ ∂ ⌻ ⍢ ⍙ ⍤ ⍫ ⌷
Alt ⍺ ⌈ ⌊ ∞ ∇ ∆ ∘ ‼ ⎕ ⍎ ⍕
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Key a s d f g h j k l ; '
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Key z x c v b n m , . /
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Tool
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⍳ ∊ ⍸ ⍷ ∪ ∩ ⊆ ⊇ ~ § π .. , ⍪ ⍴ ⌽ ⊖ ⍉
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