Info: (octave) Terminal Output

octave: Terminal Output

14.1.1 Terminal Output
----------------------

Since Octave normally prints the value of an expression as soon as it
has been evaluated, the simplest of all I/O functions is a simple
expression. For example, the following expression will display the
value of ‘pi’

pi
⊣ pi = 3.1416

This works well as long as it is acceptable to have the name of the
variable (or ‘ans’) printed along with the value. To print the value of
a variable without printing its name, use the function ‘disp’.

The ‘format’ command offers some control over the way Octave prints
values with ‘disp’ and through the normal echoing mechanism.

-- : disp (X)
-- : STR = disp (X)
Display the value of X.

For example:

disp ("The value of pi is:"), disp (pi)

⊣ the value of pi is:
⊣ 3.1416

Note that the output from ‘disp’ always ends with a newline.

If an output value is requested, ‘disp’ prints nothing and returns
the formatted output in a string.

See also: fdisp XREFfdisp.

-- : list_in_columns (ARG, WIDTH, PREFIX)
Return a string containing the elements of ARG listed in columns
with an overall maximum width of WIDTH and optional prefix PREFIX.

The argument ARG must be a cell array of character strings or a
character array.

If WIDTH is not specified or is an empty matrix, or less than or
equal to zero, the width of the terminal screen is used. Newline
characters are used to break the lines in the output string. For
example:

list_in_columns ({"abc", "def", "ghijkl", "mnop", "qrs", "tuv"}, 20)
⇒ abc mnop
def qrs
ghijkl tuv

whos ans
⇒
Variables in the current scope:

Attr Name Size Bytes Class
==== ==== ==== ===== =====
ans 1x37 37 char

Total is 37 elements using 37 bytes

See also: terminal_size XREFterminal_size.

-- : terminal_size ()
Return a two-element row vector containing the current size of the
terminal window in characters (rows and columns).

See also: list_in_columns XREFlist_in_columns.

-- : format
-- : format options
Reset or specify the format of the output produced by ‘disp’ and
Octave’s normal echoing mechanism.

This command only affects the display of numbers but not how they
are stored or computed. To change the internal representation from
the default double use one of the conversion functions such as
‘single’, ‘uint8’, ‘int64’, etc.

By default, Octave displays 5 significant digits in a human
readable form (option ‘short’ paired with ‘loose’ format for
matrices). If ‘format’ is invoked without any options, this
default format is restored.

Valid formats for floating point numbers are listed in the
following table.

‘short’
Fixed point format with 5 significant figures in a field that
is a maximum of 10 characters wide. (default).

If Octave is unable to format a matrix so that columns line up
on the decimal point and all numbers fit within the maximum
field width then it switches to an exponential ‘e’ format.

‘long’
Fixed point format with 15 significant figures in a field that
is a maximum of 20 characters wide.

As with the ‘short’ format, Octave will switch to an
exponential ‘e’ format if it is unable to format a matrix
properly using the current format.

‘short e’
‘long e’
Exponential format. The number to be represented is split
between a mantissa and an exponent (power of 10). The
mantissa has 5 significant digits in the short format and 15
digits in the long format. For example, with the ‘short e’
format, ‘pi’ is displayed as ‘3.1416e+00’.

‘short E’
‘long E’
Identical to ‘short e’ or ‘long e’ but displays an uppercase
‘E’ to indicate the exponent. For example, with the ‘long E’
format, ‘pi’ is displayed as ‘3.14159265358979E+00’.

‘short g’
‘long g’
Optimally choose between fixed point and exponential format
based on the magnitude of the number. For example, with the
‘short g’ format, ‘pi .^ [2; 4; 8; 16; 32]’ is displayed as

ans =

9.8696
97.409
9488.5
9.0032e+07
8.1058e+15

‘short eng’
‘long eng’
Identical to ‘short e’ or ‘long e’ but displays the value
using an engineering format, where the exponent is divisible
by 3. For example, with the ‘short eng’ format, ‘10 * pi’ is
displayed as ‘31.4159e+00’.

‘long G’
‘short G’
Identical to ‘short g’ or ‘long g’ but displays an uppercase
‘E’ to indicate the exponent.

‘free’
‘none’
Print output in free format, without trying to line up columns
of matrices on the decimal point. This also causes complex
numbers to be formatted as numeric pairs like this ‘(0.60419,
0.60709)’ instead of like this ‘0.60419 + 0.60709i’.

The following formats affect all numeric output (floating point and
integer types).

‘"+"’
‘"+" CHARS’
‘plus’
‘plus CHARS’
Print a ‘+’ symbol for matrix elements greater than zero, a
‘-’ symbol for elements less than zero and a space for zero
matrix elements. This format can be very useful for examining
the structure of a large sparse matrix.

The optional argument CHARS specifies a list of 3 characters
to use for printing values greater than zero, less than zero
and equal to zero. For example, with the ‘"+" "+-."’ format,
‘[1, 0, -1; -1, 0, 1]’ is displayed as

ans =

+.-
-.+

‘bank’
Print in a fixed format with two digits to the right of the
decimal point.

‘native-hex’
Print the hexadecimal representation of numbers as they are
stored in memory. For example, on a workstation which stores
8 byte real values in IEEE format with the least significant
byte first, the value of ‘pi’ when printed in ‘native-hex’
format is ‘400921fb54442d18’.

‘hex’
The same as ‘native-hex’, but always print the most
significant byte first.

‘native-bit’
Print the bit representation of numbers as stored in memory.
For example, the value of ‘pi’ is

01000000000010010010000111111011
01010100010001000010110100011000

(shown here in two 32 bit sections for typesetting purposes)
when printed in native-bit format on a workstation which
stores 8 byte real values in IEEE format with the least
significant byte first.

‘bit’
The same as ‘native-bit’, but always print the most
significant bits first.

‘rat’
Print a rational approximation, i.e., values are approximated
as the ratio of small integers. For example, with the ‘rat’
format, ‘pi’ is displayed as ‘355/113’.

The following two options affect the display of all matrices.

‘compact’
Remove blank lines around column number labels and between
matrices producing more compact output with more data per
page.

‘loose’
Insert blank lines above and below column number labels and
between matrices to produce a more readable output with less
data per page. (default).

DONTPRINTYET See also: fixed_point_format XREFfixed_point_format, *noteDONTPRINTYET DONTPRINTYET See also: fixed_point_format XREFfixed_point_format,
output_max_field_width XREFoutput_max_field_width, *noteDONTPRINTYET DONTPRINTYET DONTPRINTYET See also: fixed_point_format XREFfixed_point_format,
output_max_field_width XREFoutput_max_field_width,
output_precision XREFoutput_precision, *notesplit_long_rows:
DONTPRINTYET DONTPRINTYET DONTPRINTYET DONTPRINTYET See also: fixed_point_format XREFfixed_point_format,
output_max_field_width XREFoutput_max_field_width,
output_precision XREFoutput_precision, split_long_rows

XREFsplit_long_rows, *noteprint_empty_dimensions:
DONTPRINTYET DONTPRINTYET DONTPRINTYET DONTPRINTYET See also: fixed_point_format XREFfixed_point_format,
output_max_field_width XREFoutput_max_field_width,
output_precision XREFoutput_precision, split_long_rows

XREFsplit_long_rows, print_empty_dimensions

XREFprint_empty_dimensions, rats XREFrats.

octave: Terminal Output

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