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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.
This variable holds the most recently computed result that was not explicitly assigned to a variable. For example, after the expression
3^2 + 4^2is evaluated, the value of
ans
is 25.
Display the value of x on the stream fid. For example,
fdisp (stdout, "The value of pi is:"), fdisp (stdout, pi) -| the value of pi is: -| 3.1416Note that the output from
fdisp
always ends with a newline.
Display the value of x. For example,
disp ("The value of pi is:"), disp (pi) -| the value of pi is: -| 3.1416Note 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.
Control the format of the output produced by
disp
and Octave's normal echoing mechanism. Valid options are listed in the following table.
short
- Octave will try to print numbers with at least 5 significant figures within a field that is a maximum of 10 characters wide (not counting additional spacing that is added between columns of a matrix).
If Octave is unable to format a matrix so that columns line up on the decimal point and all the numbers fit within the maximum field width, it switches to an `e' format.
long
- Octave will try to print numbers with at least 15 significant figures within a field that is a maximum of 20 characters wide (not counting additional spacing that is added between columns of a matrix).
As will the `short' format, Octave will switch to an `e' format if it is unable to format a matrix so that columns line up on the decimal point and all the numbers fit within the maximum field width.
long e
short e
- The same as `format long' or `format short' but always display output with an `e' format. For example, with the `short e' format,
pi
is displayed as3.14e+00
.long E
short E
- The same as `format long e' or `format short e' but always display output with an uppercase `E' format. For example, with the `long E' format,
pi
is displayed as3.14159265358979E+00
.long g
short g
- Choose between normal `long' (or `short') and and `long e' (or `short e') formats based on the magnitude of the number. For example, with the `short g' format,
pi .^ [2; 4; 8; 16; 32]
is displayed asans = 3.1416 9.8696 97.409 9488.5 9.0032e+07 8.1058e+15long G
short G
- The same as `format long g' or `format short g' but use an uppercase `E' format. For example, with the `short G' format,
pi .^ [2; 4; 8; 16; 32]
is displayed asans = 3.1416 9.8696 97.409 9488.5 9.0032E+07 8.1058E+15free
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 like this `(0.604194, 0.607088)' instead of like this `0.60419 + 0.60709i'.
bank
- Print in a fixed format with two places to the right of the decimal point.
+
+
charsplus
plus
chars- Print a `+' symbol for nonzero matrix elements and a space for zero matrix elements. This format can be very useful for examining the structure of a large 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 asans = +.- -.+native-hex
- Print the hexadecimal representation 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 inhex
format is400921fb54442d18
. This format only works for numeric values.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
is01000000000010010010000111111011 01010100010001000010110100011000(shown here in two 32 bit sections for typesetting purposes) when printed in bit format on a workstation which stores 8 byte real values in IEEE format with the least significant byte first. This format only works for numeric types.
bit
- The same as
native-bit
, but always print the most significant bits first.compact
- Remove extra blank space around column number labels.
loose
- Insert blank lines above and below column number labels (this is the default).
By default, Octave will try to print numbers with at least 5 significant figures within a field that is a maximum of 10 characters wide.
If Octave is unable to format a matrix so that columns line up on the decimal point and all the numbers fit within the maximum field width, it switches to an `e' format.
If
format
is invoked without any options, the default format state is restored.