923257279754140647424
000000000000000
What you get are all the digits of the integer result. How about 100!, this time you get the floating point
answer,
9.332621544394415
E
157
The latter is because Reckon limits integers from getting too big, when they do, they are automatically
converted to floating point. You can always force a number to floating point with
F
D
. Actually, integers
are also rationals, so when you calculate
36/7
you get
3+1/7
rather than a floating point answer. This is
also true of perfect squares, eg.
Sqrt(4/9)
gives
2/3
.
When a real number can’t go, Reckon promotes it to a complex number. For example
sqrt(-2
) is not real, so
a complex result is returned. All complex numbers are complex floating point, there are no complex
fractions.
Floating point numbers in Reckon are just like those in other calculators. Reckon’s floating point number
system is internally stored in decimal (not binary IEEE754). This is also the case with most real world
calculators. Binary floating point numbers lead to problems sometimes, for example, 0.1 is finite in decimal,
but not in binary and can lead to rounding discrepancies.
Reckon uses 25 digits internally for all its scientific functions, but usually less are actually displayed on
screen [
Todo: display style format
].
Reckon supports exponents of 4 digits, going up to
10
9999
. Also the quantities
Inf
and
–Inf
are available.
Note that
1/0
is
Inf
.
NaN
s are undefined results, e.g.
0/0
is
NaN
. These values as intermediate results do not
halt evaluation.
Reckon supports some non-numerical types, including strings, e.g.
“hello”
, and array vectors,
[1 2 3]
.
Currently curly braces are not used for anything.
Unit Conversions
Reckon uses an unusual method for unit conversions. At first, it might be a bit confusing but is very simple
to use. Units are represented by their value in SI units and bound to specific variables.
All of the variables used for unit conversions are special and start with a
#
, otherwise they are same as
normal variables. Most of the unit variables are 3 letters or less. To make it easier to enter these variables
the
VAR
key enters the
#
sign and automatically engages
alpha lock
. You must disengage alpha lock
manually, unless your next key is
EXE
in which case the lock is dropped automatically.
Example: The speed of light is
#C
Enter
VARS C EXE
(no need to press
ALPHA
). You will see the value,
299792458
This is the speed of light in m/s. i.e. in SI units.
By way of example, we will convert the speed of light into miles per hour. Miles per hour is the symbol
#MPH
. The rule for unit conversions is:
Multiply by the symbol for what you have and divide by the symbol for what you want.
Example: 3 times the speed of light in miles per hour:
3 VARS C ALPHA / VARS M P H EXE
Or in RPN:
3 VARS C EXE VARS M P H EXE /
Note
: the
ALPHA
is required to release the lock. Unfortunately the divide key otherwise has the alpha
T
. in
RPN we can use
EXE
(i.e. enter) to release the lock for us.
Here is a list of the current symbols:
