Format (Dyadic) R←X⍕Y

Y must be a simple real (non-complex) numeric array. X must be a simple integer scalar or vector. R is a character array displaying the array Y according to the specification X. R has rank 1⌈⍴⍴Y and ¯1↓⍴R is ¯1↓⍴Y. If any element of Y is complex, dyadic ⍕ reports a DOMAIN ERROR.

Conformability requires that if X has more than two elements, then ⍴X must be 2ׯ1↑⍴Y. If X contains one element, it is extended to (2ׯ1↑⍴Y)⍴0,X. If X contains 2 elements, it is extended to (2ׯ1↑⍴Y)⍴X.

X specifies two numbers (possibly after extension) for each column in Y. For this purpose, scalar Y is treated as a one-element vector. Each pair of numbers in X identifies a format width (W) and a format precision (P).

If P is 0, the column is to be formatted as integers.

Examples

      5 0 ⍕ 2 3⍴⍳6
    1    2    3
    4    5    6

      4 0⍕1.1 2 ¯4 2.547
   1   2  ¯4   3

Example

If P is positive, the format is floating point with P significant digits to be displayed after the decimal point.

      4 1⍕1.1 2 ¯4 2.547
 1.1 2.0¯4.0 2.5

Example

If P is negative, scaled format is used with |P digits in the mantissa.

      7 ¯3⍕5 15 155 1555
5.00E0 1.50E1 1.55E2 1.56E3

Example

If W is 0 or absent, then the width of the corresponding columns of R are determined by the maximum width required by any element in the corresponding columns of Y, plus one separating space.

      3⍕2 3⍴10 15.2346 ¯17.1 2 3 4
 10.000 15.235 ¯17.100
  2.000  3.000   4.000

Example

If a formatted element exceeds its specified field width when W>0, the field width for that element is filled with asterisks.

      3 0 6 2 ⍕ 3 2⍴10.1 15 1001 22.357 101 1110.1
 10 15.00
*** 22.36
101******

Example

If the format precision exceeds the internal precision, low order digits are replaced by the symbol '_'.

      26⍕2*100
1267650600228229_______________.__________________________

      ⍴26⍕2*100
59

      0 20⍕÷3
 0.3333333333333333____

      0 ¯20⍕÷3
 3.333333333333333____E¯1

The shape of R is the same as the shape of Y except that the last dimension of R is the sum of the field widths specified in X or deduced by the function. If Y is a scalar, the shape of R is the field width.

      ⍴5 2 ⍕ 2 3 4⍴⍳24
2 3 20