Hello, developers,

It seems to be a bug in MATH.PP 1.1.2.2 in arcsin function. I think, this is incorrect:
if abs(x) > 1 then InvalidArgument
I added these strings:
const Epsilon = 1.0e-9;
....
if (x-1)<=Epsilon then x:=1;
if (x+1)<=Epsilon then x:=-1;

I made these changes because of InvalidArgument exception when arcsin parameter (displayed by GDB) is 1 (but, I think, it was near 1, but not 1).

Best regards,
Medvedev

But if it is larger than 1, arcsin is not defined ? You deliberately introduce an error in the calculation in this way ?

It may be better to change the code to

if abs(x)>1.0 then

Because then reals are used for the comparision, since in the case of abs(X) > 1 the '1' will probably be interpreted as an integer.

Michael.

[ Charset X-UNKNOWN unsupported, converting... ]

or abs(x+epsilon) >=1

The problem is that floats on computers are inherently inexact and if you perform a number of calculations the results becomes more inexact after every operation (I had a lot of trouble with this while implementing the str_real() routine). You should indeed work with a small epsilon to compensate for this, but the size of this epsilon depends on the size of the best real type available (for extended = 10 bytes, it could be 1.0e-9, but for extended = 8 bytes, it will be bigger).

Because then reals are used for the comparision, since in the case of abs(X) > 1 the '1' will probably be interpreted as an integer.

No, if one operand in an expression is a float, everything will be converted to a float.

Jonas

See also the numlib sources. They have a lot of those constructs to prevent such problems. They use epsilon constructs everywhere.

i have latest TV and i get this error

C:\zbyna\tv>fpc buildfv
views.pas(908,7) Error: Identifier not found "GetLockScreenCount" views.pas(5579) Fatal: There were 1 errors compiling module, stopping

Zbynek

You need the latest RTL also

Latest fv.zip that I have (24/09/01) works ok here for Mon's sources making win32 & go32 compiler && IDEs both for v10 & v11...hth J