calc: Float Formats
7.7.3 Float Formats
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Floating-point quantities are normally displayed in standard decimal
form, with scientific notation used if the exponent is especially high
or low. All significant digits are normally displayed. The commands in
this section allow you to choose among several alternative display
formats for floats.
The ‘d n’ (‘calc-normal-notation’) command selects the normal display
format. All significant figures in a number are displayed. With a
positive numeric prefix, numbers are rounded if necessary to that number
of significant digits. With a negative numerix prefix, the specified
number of significant digits less than the current precision is used.
(Thus ‘C-u -2 d n’ displays 10 digits if the current precision is 12.)
The ‘d f’ (‘calc-fix-notation’) command selects fixed-point notation.
The numeric argument is the number of digits after the decimal point,
zero or more. This format will relax into scientific notation if a
nonzero number would otherwise have been rounded all the way to zero.
Specifying a negative number of digits is the same as for a positive
number, except that small nonzero numbers will be rounded to zero rather
than switching to scientific notation.
The ‘d s’ (‘calc-sci-notation’) command selects scientific notation.
A positive argument sets the number of significant figures displayed, of
which one will be before and the rest after the decimal point. A
negative argument works the same as for ‘d n’ format. The default is to
display all significant digits.
The ‘d e’ (‘calc-eng-notation’) command selects engineering notation.
This is similar to scientific notation except that the exponent is
rounded down to a multiple of three, with from one to three digits
before the decimal point. An optional numeric prefix sets the number of
significant digits to display, as for ‘d s’.
It is important to distinguish between the current _precision_ and
the current _display format_. After the commands ‘C-u 10 p’ and ‘C-u 6
d n’ the Calculator computes all results to ten significant figures but
displays only six. (In fact, intermediate calculations are often
carried to one or two more significant figures, but values placed on the
stack will be rounded down to ten figures.) Numbers are never actually
rounded to the display precision for storage, except by commands like
‘C-k’ and ‘C-x * y’ which operate on the actual displayed text in the
Calculator buffer.
The ‘d .’ (‘calc-point-char’) command selects the character used as a
decimal point. Normally this is a period; users in some countries may
wish to change this to a comma. Note that this is only a display style;
on entry, periods must always be used to denote floating-point numbers,
and commas to separate elements in a list.
Info Catalog
calc: Grouping Digits
calc: Display Modes
calc: Complex Formats