Generic arithmetic on vectors

[Liam Healy]

What type the result should be is not easy to determine in general, as
you note. Taking the same type as the first argument is indeed a hack;
it's really just a convenience for the most common cases. What you
want to do is use grid:map-grid with either :destination (for which
you have previously made the correct object, and supplied the object
as the argument) or :destination-specification.

On Sun, Apr 19, 2015 at 3:15 PM, Harvey Stein <hjstein at gmail.com> wrote:
> In SBCL, I'm finding some generic arithmetic is returning an error.  The
> trace is below.  Basically, when I try to (antik:* x y), and x and y are
> sequences, it fails if x is of type (simple-array fixnum) and y is of type
> (simple-array double-float).
>
> The problem appears to be in generic.lisp, where *i is defined to fall
> through to (map (type-of x) #'*i x y), thus assuming that the type produced
> by the product is the same as the type of the first argument.  In general,
> that won't be the case because of the numerical tower, floating point
> contagion, etc.  Even operating on two fixnums can create a bignum, so
> operands of type (simple-array fixnum) can need to create an array of type
> (simple-array integer).
>
> Here's the trace:
>
> ~$ sbcl
> This is SBCL 1.1.14.debian, an implementation of ANSI Common Lisp.
> More information about SBCL is available at <http://www.sbcl.org/>.
>
> SBCL is free software, provided as is, with absolutely no warranty.
> It is mostly in the public domain; some portions are provided under
> BSD-style licenses.  See the CREDITS and COPYING files in the
> distribution for more information.
> * (defvar x1 (make-array 3 :element-type 'double-float :initial-contents
> '(1d0 2d0 3d0)))
>
> X1
> * (defvar i1 (make-array 3 :element-type 'fixum :initial-contents '(1 2 3)))
>
> I1
> * x1
>
> #(1.0d0 2.0d0 3.0d0)
> * i1
>
> #(1 2 3)
> * (type-of x1)
>
> (SIMPLE-ARRAY DOUBLE-FLOAT (3))
> * (type-of i1)
>
> (SIMPLE-VECTOR 3)
> * (ql:quickload "antik")
> To load "antik":
>   Load 1 ASDF system:
>     antik
> ; Loading "antik"
> .........
> ("antik")
> * (antik:* i1 x1)
>
> #(1.0 4.0 9.0)
> * (antik:* x1 i1)
>
> #(1.0 4.0 9.0)
> * (antik:* x1 (coerce i1 '(vector fixnum)))
>
> #(1.0 4.0 9.0)
> * (antik:* (coerce i1 '(vector fixnum)) x1 )
>
> debugger invoked on a TYPE-ERROR in thread
> #<THREAD "main thread" RUNNING {1002A8AF83}>:
>   The value 1.0d0 is not of type FIXNUM.
>
> Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.
>
> restarts (invokable by number or by possibly-abbreviated name):
>   0: [ABORT] Exit debugger, returning to top level.
>
> (SB-IMPL::OPTIMIZED-DATA-VECTOR-SET #<unavailable argument> #<unavailable
> argument> #<unavailable argument>)
> 0] backtrace
>
> Backtrace for: #<SB-THREAD:THREAD "main thread" RUNNING {1002A8AF83}>
> 0: (SB-IMPL::OPTIMIZED-DATA-VECTOR-SET #<unavailable argument> #<unavailable
> argument> #<unavailable argument>)
> 1: ((FLET SB-IMPL::F :IN SB-IMPL::%MAP-TO-VECTOR) 1 1.0d0)
> 2: (SB-IMPL::%MAP-FOR-EFFECT #<CLOSURE (FLET SB-IMPL::F :IN
> SB-IMPL::%MAP-TO-VECTOR) {7FFFF6BBF73B}> (#(1 2 3) #(1.0d0 2.0d0 3.0d0)))
> 3: (SB-IMPL::%MAP-TO-VECTOR (SIMPLE-ARRAY FIXNUM (3))
> #<STANDARD-GENERIC-FUNCTION ANTIK::*I (10)> (#(1 2 3) #(1.0d0 2.0d0 3.0d0)))
> 4: (REDUCE #<STANDARD-GENERIC-FUNCTION ANTIK::*I (10)> (#(1 2 3) #(1.0d0
> 2.0d0 3.0d0)))
> 5: (SB-INT:SIMPLE-EVAL-IN-LEXENV (ANTIK:* (COERCE I1 (QUOTE (VECTOR
> FIXNUM))) X1) #<NULL-LEXENV>)
> 6: (EVAL (ANTIK:* (COERCE I1 (QUOTE (VECTOR FIXNUM))) X1))
> 7: (INTERACTIVE-EVAL (ANTIK:* (COERCE I1 (QUOTE (VECTOR FIXNUM))) X1) :EVAL
> NIL)
> 8: (SB-IMPL::REPL-FUN NIL)
> 9: ((LAMBDA NIL :IN SB-IMPL::TOPLEVEL-REPL))
> 10: (SB-IMPL::%WITH-REBOUND-IO-SYNTAX #<CLOSURE (LAMBDA NIL :IN
> SB-IMPL::TOPLEVEL-REPL) {1003C615BB}>)
> 11: (SB-IMPL::TOPLEVEL-REPL NIL)
> 12: (SB-IMPL::TOPLEVEL-INIT)
> 13: ((FLET #:WITHOUT-INTERRUPTS-BODY-54 :IN SAVE-LISP-AND-DIE))
> 14: ((LABELS SB-IMPL::RESTART-LISP :IN SAVE-LISP-AND-DIE))
>
> 0]
>
>
> --
> Harvey J. Stein
> hjstein at gmail.com
> http://www.linkedin.com/in/harveyjstein
> Selected papers and presentations available at:
> http://ssrn.com/author=732372