7.3. BINARY TABLE EXTENSION

67

field consists of a string of w asterisk (*) characters. In all cases, d specifies the number

of digits to appear to the right of the decimal point. The F format code output field

consists of w-d-1 characters containing zero or more leading spaces followed by a minus

sign if the internal datum is negative followed by the absolute magnitude of the internal

datum in the form of an unsigned integer constant. These characters are followed by a

decimal point (`.') and d characters giving the fractional part of the internal datum,

rounded by the normal rules of arithmetic to d fractional digits. For the E and D format

codes, an exponent is taken such that the fraction 0.1 ≤ |datum|/10exponent < 1.0. The

fraction (with appropriate sign) is output with an F format of width w - e - 2 characters

with d characters after the decimal followed by an E or D followed by the exponent as

a signed e + 1 character integer with leading zeros as needed. The default value of e

is 2 when the Ee portion of the format code is omitted. If the exponent value will not

fit in e + 1 characters but will fit in e + 2 then the E (or D) is omitted and the wider

field used. If the exponent value will not fit (with a sign character) in e + 2 characters,

then the entire w-character output field is filled with asterisks (*). The ES format code

is processed in the same manner as the E format code except that the exponent is taken

so that 1.0 ≤ fraction < 10. The EN format code is processed in the same manner as the

E format code except that the exponent is taken to be an integer multiple of 3 and so

that 1.0 ≤ fraction < 1000.0. All real format codes have number base 10. There is no

difference between E and D format codes on input other than an implication with the

latter of greater precision in the internal datum.

The Gw.dEe format code may be used with data of any type. For data of type integer,

logical, or character, it is equivalent to Iw, Lw, or Aw, respectively. For data of type real,

it is equivalent to an F format (with different numbers of characters after the decimal)

when that format will accurately represent the value and is equivalent to an E format

when the number (in absolute value) is either very small or very large. Specifically, for

real values outside the range 0.1 - 0.5 × 10-d-1 ≤ value < 10d - 0.5, it is equivalent

to Ew.dEe. For real values within the above range, it is equivalent to Fw .d followed by

2 + e spaces, where w' = w - e - 2 and d' = d - k for k = 0, 1, . . . , d if the real datum

k-1

-d

-d

k

) ≤

).

(1 - 0.5×10

value ≤ 10

(1 - 0.5×10

value lies in the range 10

Complex data If the table column contains complex data (with TFORMn = 'rC', or

'rM') then the may be displayed with any of the real data formats as described above.

The same format is used for the real and imaginary parts. It is recommended that the

2 values be separated by a comma and enclosed in parentheses with a total field width

of 2w + 3.

7.3.5

Variable-Length Arrays

One of the most attractive features of binary tables is that any field of the table can be

an array. In the standard case this is a fixed size array, i.e., a fixed amount of storage

FITS Standard