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May 2013

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[GSLL-devel] Fixing up make-grid-data for clisp (was making copy-to working in clisp+grid: fix to element-type)
by Mirko Vukovic 26 Dec '13

26 Dec '13

This is a follow up on my posted fix to copy-to. For some reason this has triggered another error. I do not understand how that other error is triggered. The error and the fix are discussed at the bottom of the email On Fri, Jan 4, 2013 at 10:39 AM, Mirko Vukovic <mirko.vukovic(a)gmail.com>wrote: > The following works in sbcl+grid: > > (copy-to (make-array 2 :element-type 'double-float :initial-contents > '(1.0d0 2.0d0)) 'grid:foreign-array) > > But it does not work in clisp+grid. > > The root cause lies in the function grid/array.lisp/element-type. It uses > `(array-element-type grid)'. > > But this can present a problem. Quoting hyperspec: > > (Because of *array* <http://26_glo_a.htm#array> *upgrading*, this *type > specifier* <http://26_glo_t.htm#type_specifier> can in some cases denote > a *supertype* <http://26_glo_s.htm#supertype> of the *expressed array > element type* <http://26_glo_e.htm#expressed_array_element_type> of the * > array*.) > > In CLISP, array-element-type returns `T' when passed #(1d0 2d0) > > It returns T even when passed a simple array: > > (array-element-type (make-array 2 :element-type 'double-float > :initial-contents > '(1.0d0 2.0d0) > :adjustable nil > :fill-pointer nil > :displaced-to nil) ) > > The proposed fix is > > (defmethod element-type ((grid array)) > (type-of (row-major-aref grid 0)) > #+skip(array-element-type grid)) > > Now copy-to works in clisp as well. > > Mirko > > > After finishing this, I recompiled afresh, and got another error that I traced to make-grid-data and make-array In clisp, make-array will return an array of NIL's even if the element-type is specified as double float. In SBCL make-array will return an array filled with 1d0. I had to add some clisp specific code to make-grid-data in order for it to initialize properly. First, a helper function: (defun default-element (element-type) "Return a default element depending on element-type " (let ((a-list '((double-float . 1d0) (symbol . T)))) (let ((match (cdr (assoc element-type a-list)))) (assert match () "Default element type undefined for element-type ~a" element-type) match))) And second, a bit of set-up code in make-grid-data. I broke apart the (let* statement to provide an explicit initial element if it has not been specified already: (defmethod make-grid-data ((type (eql 'array)) dimensions rest-spec &key (initial-element nil initial-element-p) (initial-contents nil initial-contents-p)) (let ((element-type (top-spec-type rest-spec))) #+clisp (unless (or initial-element-p initial-contents-p) (setf initial-element (default-element element-type) initial-element-p t)) (let ((array ... UNCHANGED Summary: To fix to copy-to, I modified (defmethod element-type ((grid array)) For some unknown reason, that triggered an error in the array initialization routine. To fix that, I had to add code to make-grid-data, so that it fills double-float arrays with 0d0 instead of NIL's I will continue using this code to see if there are additional problems. BTW, I realize that CLISP is not a preferred platform for speedy computation, but that is what I use on Windows, until SBCL gets officially ported to it. And in addition, it is a nice cross-check on portability. Mirko

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[GSLL-devel] making copy-to working in clisp+grid: fix to element-type
by Mirko Vukovic 26 Dec '13

26 Dec '13

The following works in sbcl+grid: (copy-to (make-array 2 :element-type 'double-float :initial-contents '(1.0d0 2.0d0)) 'grid:foreign-array) But it does not work in clisp+grid. The root cause lies in the function grid/array.lisp/element-type. It uses `(array-element-type grid)'. But this can present a problem. Quoting hyperspec: (Because of *array* <26_glo_a.htm#array> *upgrading*, this *type specifier*<26_glo_t.htm#type_specifier>can in some cases denote a *supertype* <26_glo_s.htm#supertype> of the *expressed array element type*<26_glo_e.htm#expressed_array_element_type>of the *array*.) In CLISP, array-element-type returns `T' when passed #(1d0 2d0) It returns T even when passed a simple array: (array-element-type (make-array 2 :element-type 'double-float :initial-contents '(1.0d0 2.0d0) :adjustable nil :fill-pointer nil :displaced-to nil) ) The proposed fix is (defmethod element-type ((grid array)) (type-of (row-major-aref grid 0)) #+skip(array-element-type grid)) Now copy-to works in clisp as well. Mirko

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