On 9/4/06, Charles R Harris <[EMAIL PROTECTED]> wrote:
The problem is somewhere in this bit of code:
// f will be a double
<snip>
On 9/4/06, Sebastian Haase < [EMAIL PROTECTED]> wrote:Paulo J. S. Silva wrote:
> Once again, the information that singed zero is part of IEEE standard is
> in the paper I cited in my last message.
>
> It is very important to be able to compute the sign of an overflowed
> quantity in expressions like 1/x when x goes to zero.
>
> Best,
>
> Paulo
Hi,
This is all very interesting ( and confusing (to me, maybe others) at
the same time ...) ...
Question 0: Are you sure this is not a bug ?
>>> N.array([66]).round(-1)
[60]
That does look like a bug.
>>> array([66]).round(-1)
array([60])
>>> array([66.]).round(-1)
array([ 70.])
I suspect it is related to the integer data type of the first example. The code probably does something like this:
round(66/10)*10
and 66/10 == 6 in integer arithmetic.
The problem is somewhere in this bit of code:
// f will be a double
f = PyFloat_FromDouble(power_of_ten(decimals));
if (f==NULL) return NULL;
// op1 will be division
ret = PyObject_CallFunction(op1, "OOO", a, f, out);
if (ret==NULL) goto finish;
// round in place.
tmp = PyObject_CallFunction(n_ops.rint, "OO", ret, ret);
if (tmp == NULL) {Py_DECREF(ret); ret=NULL; goto finish;}
I suspect the problem is the division, which has integer 'a', double 'f', and integer 'out'. Integer out is probably the killer. Let's see:
# use doubles for output
>>> out = zeros(1)
>>> array([66]).round(decimals=-1, out=out)
array([ 70.])
yep, that's the problem
Chuck.
if (f==NULL) return NULL;
// op1 will be division
ret = PyObject_CallFunction(op1, "OOO", a, f, out);
if (ret==NULL) goto finish;
// round in place.
tmp = PyObject_CallFunction(n_ops.rint, "OO", ret, ret);
if (tmp == NULL) {Py_DECREF(ret); ret=NULL; goto finish;}
I suspect the problem is the division, which has integer 'a', double 'f', and integer 'out'. Integer out is probably the killer. Let's see:
# use doubles for output
>>> out = zeros(1)
>>> array([66]).round(decimals=-1, out=out)
array([ 70.])
yep, that's the problem
Chuck.
<snip>
------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
_______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
