format(keyword)#

Purpose#

Controls the format of matrices and numbers printed out with print statements.

Format#

format [[/typ]] [[/fmted]] [[/mf]] [[/jnt]] [[f,p]]

Parameters

/typ:

(literal) symbol type flag(s). Indicate which symbol types you are setting the output format for.

/mat, /sa, /str

Formatting parameters are maintained separately for matrices and arrays (/mat), string arrays (/sa), and strings (/str).You can specify more than one /typ flag; the format will be set for all types indicated. If no /typ flag is listed, format assumes /mat.
/fmted:

(literal) enable formatting flag.

/on, /off

Enable/disable formatting. When formatting is disabled, the contents of a variable are dumped to the screen in a raw format. /off is currently supported only for strings. raw format for strings means that the entire string is printed, starting at the current cursor position. When formatting is enabled for strings, they are handled the same as string arrays. This shouldn’t be too surprising, since a string is actually a 1x1 string array.
/mf:

(literal) matrix row format flag.

/m0

no delimiters before or after rows when printing out matrices.

/m1 or /mb1

print 1 carriage return/line feed pair before each row of a matrix with more than 1 row.

/m2 or /mb2

print 2 carriage return/line feed pairs before each row of a matrix with more than 1 row.

/m3 or /mb3

print Row 1, Row 2, ... before each row of a matrix with more than one row.

/ma1

print 1 carriage return/line feed pair after each row of a matrix with more than 1 row.

/ma2

print 2 carriage return/line feed pairs after each row of a matrix with more than 1 row.

/a1

print 1 carriage return/line feed pair after each row of a matrix.

/a2

print 2 carriage return/line feed pairs after each row of a matrix.

/b1

print 1 carriage return/line feed pair before each row of a matrix.

/b2

print 2 carriage return/line feed pairs before each row of a matrix.

/b3

print Row 1, Row 2, ... before each row of a matrix.
/jnt:

(literal) matrix element format flag - controls justification, notation and trailing character.

Right-Justified

/rd

Signed decimal number in the form ####.####, where #### is one or more decimal digits. The number of digits before the decimal point depends on the magnitude of the number, and the number of digits after the decimal point depends on the precision. If the precision is 0, no decimal point will be printed.

/re

Signed number in the form #.##E±###,where # is one decimal digit, ## is one or more decimal digits depending on the precision, and ### is three decimal digits. If precision is 0, the form will be [-]#E±### with no decimal point printed.

/ro

This will give a format like /rd or /re depending on which is most compact for the number being printed. A format like /re will be used only if the exponent value is less than -4 or greater than the precision. If a /re format is used, a decimal point will always appear. The precision signifies the number of significant digits displayed.

/rz

This will give a format like /rd or /re depending on which is most compact for the number being printed. A format like /re will be used only if the exponent value is less than -4 or greater than the precision. If a /re format is used, trailing zeros will be suppressed and a decimal point will appear only if one or more digits follow it. The precision signifies the number of significant digits displayed.

Left-Justified

/ld

Signed decimal number in the form [-]####.####, where #### is one or more decimal digits. The number of digits before the decimal point depends on the magnitude of the number, and the number of digits after the decimal point depends on the precision. If the precision is 0, no decimal point will be printed. If the number is positive, a space character will replace the leading minus sign.

/le

Signed number in the form [-]#.##E±###, where # is one decimal digit, ## is one or more decimal digits depending on the precision, and ### is three decimal digits. If precision is 0, the form will be [-]#E±### with no decimal point printed. If the number is positive, a space character will replace the leading minus sign.

/lo

This will give a format like /ld or /le depending on which is most compact for the number being printed. A format like /le will be used only if the exponent value is less than -4 or greater than the precision. If a /le format is used, a decimal point will always appear. If the number is positive, a space character will replace the leading minus sign. The precision specifies the number of significant digits displayed.

/lz

This will give a format like /ld or /le depending on which is most compact for the number being printed. A format like /le will be used only if the exponent value is less than -4 or greater than the precision. If a /le format is used, trailing zeros will be suppressed and a decimal point will appear only if one or more digits follow it. If the number is positive, a space character will replace the leading minus sign. The precision specifies the number of significant digits displayed.

Trailing Character

The following characters can be added to the /jnt parameters above to control the trailing character if any:

format /rdn 1,3;

s

The number will be followed immediately by a space character. This is the default.

c

The number will be followed immediately by a comma.

t

The number will be followed immediately by a tab character.

n

No trailing character.
f:

(scalar) controls the field width.

p:

(scalar) controls the precision.

Examples#

For the examples below we will use a matrix elements of different magnitudes to more clearly show the differences between the different formatting options. This code will create that matrix:

rndseed 642354;
x = rndn(3, 3);
x[2, 2] = x[2, 2] .* 1e8;
x[1, 1] = x[1, 1] .* 1e-12;
x[3, 1] = x[3, 1] .* 1e-3;

// GAUSS default format
format /m1 /ros 16,8;
print x;

-1.1777603e-12      -0.92450840      -0.39442934
  -0.023389275        70796411.       0.19679620
-0.00076864628       0.47818734      -0.13173939

/*
** r: right justified d: decimal
** 16: field width is 16 places
** 8: print 8 digits after the decimal point
*/
format /rd 16,8;
print x;

  0.00000000      -0.92450840      -0.39442934
-0.02338927 70796411.12351108       0.19679620
 -0.00076865       0.47818734      -0.13173939

As mentioned in the Remarks section, if the number is too large to fit in the field, the field size will be ignored. The \([2,2]\) element in the matrix above, needs a field width of 17 to print the 8 places after the decimal plus the 8 in front of the decimal and one for the decimal place. This causes the \([2,3]\) element to be bumped over 1 space.

/*
** r: right justified.
** z: decimal or scientific notation, whichever is more compact.
** 16: field width is 16 places
** 4: 4 digits after the decimal point, or 4 significant digits.
*/
format /m3 /rz 16,4;
print x;

Row 1
      -1.178e-12          -0.9245          -0.3944
Row 2
        -0.02339         7.08e+07           0.1968
Row 3
      -0.0007686           0.4782          -0.1317

/*
** m1: single new line after each row.
** l: left-justified.
** z: decimal or scientific notation, whichever is more compact.
** 12: field width is 12 places
** 4: 4 digits after the decimal point, or 4 significant digits.
*/
format /m1 /lz 12,4;
print x;

-1.178e-12   -0.9245      -0.3944
-0.02339      7.08e+07     0.1968
-0.0007686    0.4782      -0.1317

/*
** r: right-justified.
** e: scientific notation.
** c: follow each element with a comma.
** 12: field width is 12 places
** 4: 4 significant digits.
*/
format /rec 12,4;
print x;

-1.1778e-12, -9.2451e-01, -3.9443e-01,
-2.3389e-02,  7.0796e+07,  1.9680e-01,
-7.6865e-04,  4.7819e-01, -1.3174e-01,

Remarks#

  • For numeric values in matrices, p sets the number of significant digits to be printed. For string arrays, strings, and character elements in matrices, p sets the number of characters to be printed. If a string is shorter than the specified precision, the entire string is printed. For string arrays and strings, p = -1 means print the entire string, regardless of its length p = -1 is illegal for matrices; setting p >= 8 means the same thing for character elements.

  • The /xxx slash parameters are optional. Field and precision are optional also, but if one is included, then both must be included. For example:

    /*
** /xxx slash parameters omitted.
** field = 8, precision = 4
*/
format 8,4;

  • Slash parameters, if present, must precede the field and precision parameters.

  • A format(keyword) statement stays in effect until it is overridden by a new format statement. The slash parameters may be used in a print statement to override the current default.

    rndseed 7986987;

x = rndn(2, 2);

// l: left justified, e: scientific notation, c: follow with a comma
print /lec x;

// r: right justified, d: decmial notation, t: follow with a tab
print /rdt x;

    will return:

    3.77117954e-01 ,-1.49080079e-01 ,
-3.94036154e-01 ,-6.26591191e-01 ,

         0.37711795             -0.14908008
         -0.39403615            -0.62659119

  • f and p may be any legal expressions that return scalars. Non integers will be truncated to integers.

    digits = 2;
format /rd digits*4, digits;
print x;

    will return:

     0.38    -0.15
-0.39    -0.63

  • The total width of field will be overridden if the number is too big to fit into the space allotted. For instance, format /rds 1,0 can be used to print integers with a single space between them, regardless of the magnitudes of the integers.

  • Complex numbers are printed with the sign of the imaginary half separating them and an “i” appended to the imaginary half. Also, the field parameter refers to the width of field for each half of the number, so a complex number printed with a field of 8 will actually take (at least) 20 spaces to print. The character printed after the imaginary part can be changed (for example, to a “j”) with the sysstate() function, case 9.

  • The default when GAUSS is first started is:

    format /mb1 /ros 16,8;

  • If character elements are to be printed, the precision should be at least 8 or the elements will be truncated. This does not affect the string data type.

See also

Functions formatcv(), formatnv(), print, output

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