IP() on negative number - issue

[primer]

Hello,
I found there is an issue with IP() function (both in home and CAS).
IP() stands for "Integer Part", ok...
but the "integer part" function is defined in math in that way :
It's the function that take a real number and return an integer n with n ≤ x < n+1.

IP(-1.5) returns -1 while the "integer part of -1.5" is -2 according to definition.
so IP() is wrong on negative numbers.

I know FLOOR() does the job, but it's a question of vocabulary.
it's confusing for math users/students.
IP() should return the same as FLOOR().
if you want a function that return -1 here you should use TRUNCATE(-1.5 ,0), not IP(-1.5)

[salvomic]

hi,
see here in Wolfram Alpha for definition.
IntegerPart[-1.5] returns -1 (see here).
Also in HP15C: Int(-1.5) I get -1
In HP 50g: IP(-1.5) -> -1 also...

Salvo

[toml_12953]

(11-28-2017 09:58 PM)primer Wrote:  Hello,
I found there is an issue with IP() function (both in home and CAS).
IP() stands for "Integer Part", ok...
but the "integer part" function is defined in math in that way :
It's the function that take a real number and return an integer n with n ≤ x < n+1.

IP(-1.5) returns -1 while the "integer part of -1.5" is -2 according to definition.
so IP() is wrong on negative numbers.

I know FLOOR() does the job, but it's a question of vocabulary.
it's confusing for math users/students.
IP() should return the same as FLOOR().
if you want a function that return -1 here you should use TRUNCATE(-1.5 ,0), not IP(-1.5)

No, IP returns the integer part only. It just lops off any decimal. Think of it as CEIL instead of FLOOR.

[cyrille de brébisson]

Hello,

IP and FP are NOT math functions, they are programming functions. And they do work as intended, cuttting off what is on the right or left of the decimal point.

FLOOR and CEIL are math functions and do respect the rule that you stated.

This is why they are 3 (FP excluded) functions to deal with this and not two.

Cheers,
Cyrille