I sometimes get requests to add functions to Console Calculator. I have many functions built-in to CCalc, but of course many more could be imagined. Therefor, I made it possible to define your own functions. I previously posted a short list of a few useful functions one might define: Useful Console Calculator functions.

I received a request today for a more advanced `round()`

function. CCalc already includes a `round()`

function, and it always rounds to the nearest integer. The request I received was to support rounding to a specified decimal place:

`round(2.535) = 3`

round(2.535, 1) = 2.5

round(2.535, 2) = 2.54

In CCalc, function names may be overloaded, similar to C++, such that `round(x)`

is a different function from `round(x,n)`

since they take different number of input arguments. Although `round(x)`

is a built-in CCalc function, `round(x,n)`

is not – so let’s define it!

`round(x,n) = round(x*10^n)/(10^n)`

This new round function will round the number `x`

to the nearest `n`

decimal places. Very nice!

Hawkeron Friday 26, 2010This is indeed very useful. Many thanks.

I have never used a function in CC with 2 parameters before.

This doesn’t work exactly as expected with the “European decimal character” option selected.

> round(x,n) = round(x*10^n)/(10^n)

** ERROR: invalid argument: x.n **

The option appears to literally swap dot and comma before the input is parsed.

I think this is a bug and that the swapping should be done when parsing and only if the comma is a decimal separator, but not if it is a variable separator.

CCalcon Friday 26, 2010When you use european mode, you have to use the period instead of comma for everything. So try round(x.n) instead and it should work for you. I know it is a bit strange, but otherwise it is difficult to tell when a comma is used as a decimal separator or when it separates arguments in a function.

Brron Friday 26, 2010Great! Thanks a lot!

Hawkeron Friday 26, 2010Yes, I realize now that you can’t have the same character for decimal separator and argument separator. But honestly I find the dot very awkward when used as the argument separator 🙂

One way of doing this is going the spreadsheet way.

They usually change the argument separator to ; (semicolon) when in european mode.

Hawkeron Friday 26, 2010And the round(x,n) function of course works also with negative numer of decimals.

Rounding to the nearest hundred goes like this:

round(279,-2) = 300

Very nice 🙂

CCalcon Friday 26, 2010“They usually change the argument separator to ; (semicolon) when in european mode.”

Hmm… I didn’t know about that, I’m not very familiar with european standards in that regard. Unfortunately, I already use the semicolon to separate multiple entries in a single line.