if 0 {Richard Suchenwirth 2002-12-29 - Letter and Legal paper formats are popular in the US and other places. In Europe and elsewhere, the most widely used paper format is called A4. To find out how big a paper format is, one can measure an instance with a ruler, or look up appropriate documentation. The A formats (DKF - I believe these are defined in a DIN document somewhere...) can also be deduced from the following axioms:
How much this ratio is, can easily be computed if we consider that A(n) is produced from A(n-1) by halving it parallel to the shorter side, so
2a : b = b : a, 2 a2 = b2, b=sqrt(2) a, hence b : a = sqrt(2) : 1
So here is my implementation, which returns a list of height and width in centimeters (10000 cm2 = 1 m2) with two fractional digits, which delivers a sufficient precision of 1/10 mm: }
proc paperA n {
set w [expr {sqrt(10000/(pow(2,$n) * sqrt(2)))}]
set h [expr {$w * sqrt(2)}]
format "%.2f %.2f" $h $w
}
% paperA 4
29.73 21.02Detailed info on the format A, which is from ISO 216, can be found here [L1 ]. Michael Schlenker - Quote: "The United States and Canada are today the only industrialized nations in which the ISO standard paper sizes are not yet widely used. In U.S. office applications, the paper formats "Letter" (216 × 279 mm), "Legal" (216 × 356 mm), "Executive" (190 × 254 mm), and "Ledger/Tabloid" (279 × 432 mm) are widely used today. There exists also an American National Standard ANSI/ASME Y14.1 for technical drawing paper sizes A (216 × 279 mm), B (279 × 432 mm), C (432 × 559 mm), D (559 × 864 mm), E (864 × 1118 mm), and there are many other unsystematic formats for various applications in use. The "Letter", "Legal", "Tabloid", and other formats (although not these names) are defined in the American National Standard ANSI X3.151-1987. "