[CLN-list] Anomaly when integer zero combined with extended float.

[Ray Buvel]

I ran across an anomaly in CLN that occurs when an integer zero value
is combined with an extended precision floating point number.
Consider the following

cl_R a,b,r;

Now assign a cl_I variable whose value is zero to a, and a high
precision cl_LF value to b.  Then perform any of the following
operations.

r = a * b;
r = b * a;
r = a / b;

In every case, the precision degrades to the default value.  However,
if the integer value in a is anything other than zero, the result has
the precision of b.

Since this only occurs for multiply and divide, I suspect it may be
due to some shortcut that is taken when one of the operands is zero.

The same anomaly occurs if the variables are declared cl_N and operand
b is a high precision floating point complex number.

The simplest way to demonstrate this behavior is to use the clnum
Python module.  The following session is on a 64-bit platform with
version 1.1.9 of CLN.

>>> from clnum import mpf
>>> x=mpf(1,50)
>>> x
mpf('1.0',55)
>>> 0*x  # Results in default precision
mpf('0.0',36)
>>> 1*x  # Preserves the precision
mpf('1.0',55)

Ray Buvel

P.S.  Is there another way to report anomalies other than posting to the list?