#2104 Problem 383 in rtest16 fails

[Anonymous]

After building sbcl-1.0.43 on Ubuntu maverick x86_64 and runing run-tests.sh I got :

Finished running tests.
Status:
Expected failure: packages.impure.lisp / USE-PACKAGE-CONFLICT-SET
Expected failure: packages.impure.lisp / IMPORT-SINGLE-CONFLICT
ok
//apparent success (reached end of run-tests.sh normally)

Making distclean in maxima-5.22.1-directory and configure/make I started make check and got:
...
Running tests in rtest16:
********************** Problem 383 ***************
Input:
block([numer : true], is(abs(zeta(%i + 3)
- (1.10721440843141 - .1482908671781754 %i)) < 1.e-15))

Result:
false

This differed from the expected result:
true

462/463 tests passed
...
and in wxmaxima 0.8.5:

(%i1) build_info()$
Maxima version: 5.22.1
Maxima build date: 20:40 11/8/2010
Host type: x86_64-unknown-linux-gnu
Lisp implementation type: SBCL
Lisp implementation version: 1.0.43

(%i2) is(abs(zeta(%i + 3) - (1.10721440843141 - .1482908671781754 %i)) < 1.e-15);
incorrect syntax: %I is not an infix operator
1482908671781754 %i)
^
(%i2) is(abs(zeta(%i + 3) - (1.10721440843141 - .1482908671781754*%i)) < 1.e-15);
(%o2) false

(%i3) if numer#false then numer:false else numer:true;
(%o3) true

(%i4) abs(zeta(%i + 3) - (1.10721440843141 - .1482908671781754*%i));
(%o4) 3.3157171357748244*10^-9

which is huge compared to 1.e-15.

[Raymond Toy]

This is really an issue with how sbcl computes (cl:expt 2 #c(1d0 2d0)). I think sbcl computes x^y using exp(y*log(x)). Since x here is an integer log(x) is a single-float, and hence the result only has single-float accuracy, even though the result is returned as a double-float.

I have heard from from sbcl developers that this will be fixed.

This was also discussed in the mailing list, and it was agreed to let the underlying Lisps fix this.

Marking as Pending/Wontfix.

[SourceForge Robot]

This Tracker item was closed automatically by the system. It was
previously set to a Pending status, and the original submitter
did not respond within 14 days (the time period specified by
the administrator of this Tracker).