System Variable PP: Difference between revisions

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       ⎕PP
       ⎕PP
10
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)
</pre>
</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.
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.

Revision as of 20:40, 21 August 2015

⎕PP - Print Precision

⎕PP Print Precision
⎕PP←'VALUE'

System Variable ⎕PP or Quad PP refers to Print Precision. In NARS, 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)

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 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
Alt+Shift ⍪ ≡ ≢ ⍒ ⍋ ⌽ ⍉ ⊖ ⍟ ⍱ ⍲ ⍠ ⌹
Alt ⋄ ¨ ¯ < ≤ ∅ ≥ > ≠ ∨ ∧ × ÷
Shift ~ ! @ # $ % ^ & * ( ) _ +
Key ` 1 2 3 4 5 6 7 8 9 0 - =
Alt+Shift ⍷ √ ⍨ ⍸ ⍥ ⍣ ⍞ ⍬ ⊣
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 ⍺ ⌈ ⌊ ∞ ∇ ∆ ∘ ‼ ⎕ ⍎ ⍕
Shift A S D F G H J K L : "
Key a s d f g h j k l ; '
Alt+Shift ⊆ ⊇ χ ⍡ ⍭ ⊙
Alt ⊂ ⊃ ∩ ∪ ⊥ ⊤ ⍦ ⍝ ⍀ ⌿
Shift Z X C V B N M < > ?
Key z x c v b n m , . /
NARS 2000 Lang
Tool
Bar 		← → + - × ÷ * ⍟ ⌹ ○ ! ? √ | ⌈ ⌊ ⊥ ⊤ ⊣ ⊢
≡ ≢ < ≤ = ≥ > ≠ ∨ ∧ ⍱ ⍲ ↑ ↓ ⊂ ⊃ ⌷ ⍋ ⍒
⍳ ∊ ⍸ ⍷ ∪ ∩ ⊆ ⊇ ~ § π .. , ⍪ ⍴ ⌽ ⊖ ⍉
/ \ ⌿ ⍀ ⊙ ¨ ⍨ ⍤ ⍣ ⍡ ⍥ ⍦ . ∘ ⍠ ‼ ⌻ ∂ ∫ ⍞ ⎕ ⍎ ⍕
⋄ ⍝ ∇ ∆ ⍙ _ ⍺ ⍵ ¯ ⍬ ∞ ∅
Second Row i j k i j k l g p r v x

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