Theory Gram_Schmidt_IArrays
section‹Gram Schmidt over IArrays›
theory Gram_Schmidt_IArrays
imports
QR_Decomposition
Matrix_To_IArray_QR
begin
subsection‹Some previous definitions, lemmas and instantiations about iarrays›
definition iarray_of_iarray_to_list_of_list :: "'a iarray iarray => 'a list list"
where "iarray_of_iarray_to_list_of_list A = map IArray.list_of (map ((!!) A) [0..<IArray.length A])"
instantiation iarray :: (scaleR) scaleR
begin
definition "scaleR_iarray k A = IArray.of_fun (λi. k *⇩R (A !! i)) (IArray.length A)"
instance proof qed
end
instantiation iarray :: (times) times
begin
definition "times_iarray A B = IArray.of_fun (λi. A!!i * B !! i) (IArray.length A)"
instance proof qed
end
lemma plus_iarray_component:
assumes iA: "i<IArray.length A"
and iB: "i<IArray.length B"
shows "(A+B) !! i = A!!i + B!!i"
proof (unfold plus_iarray_def Let_def )
have "IArray.of_fun
(λa. IArray.of_fun (λa. if a < IArray.length A then A !! a else 0) (max (IArray.length A) (IArray.length B)) !! a +
IArray.of_fun (λa. if a < IArray.length B then B !! a else 0) (max (IArray.length A) (IArray.length B)) !! a)
(max (IArray.length A) (IArray.length B)) !!
i = IArray.of_fun (λa. if a < IArray.length A then A !! a else 0) (max (IArray.length A) (IArray.length B)) !! i +
IArray.of_fun (λa. if a < IArray.length B then B !! a else 0) (max (IArray.length A) (IArray.length B)) !! i"
by (rule of_fun_nth, metis iB less_max_iff_disj)
also have "...= (λa. if a < IArray.length A then A !! a else 0) i +
(λa. if a < IArray.length B then B !! a else 0) i"
using of_fun_nth[of i "(max (IArray.length A) (IArray.length B))"] using iB by simp
also have "...= A!!i + B !! i" using iA iB by simp
finally show "IArray.of_fun
(λa. IArray.of_fun (λa. if a < IArray.length A then A !! a else 0) (max (IArray.length A) (IArray.length B)) !! a +
IArray.of_fun (λa. if a < IArray.length B then B !! a else 0) (max (IArray.length A) (IArray.length B)) !! a)
(max (IArray.length A) (IArray.length B)) !!
i =
A !! i + B !! i" .
qed
lemma minus_iarray_component:
assumes iA: "i<IArray.length A"
and iB: "i<IArray.length B"
shows "(A-B) !! i = A!!i - B!!i"
proof (unfold minus_iarray_def Let_def )
have "IArray.of_fun
(λa. IArray.of_fun (λa. if a < IArray.length A then A !! a else 0) (max (IArray.length A) (IArray.length B)) !! a -
IArray.of_fun (λa. if a < IArray.length B then B !! a else 0) (max (IArray.length A) (IArray.length B)) !! a)
(max (IArray.length A) (IArray.length B)) !!
i = IArray.of_fun (λa. if a < IArray.length A then A !! a else 0) (max (IArray.length A) (IArray.length B)) !! i -
IArray.of_fun (λa. if a < IArray.length B then B !! a else 0) (max (IArray.length A) (IArray.length B)) !! i"
by (rule of_fun_nth, metis iB less_max_iff_disj)
also have "...= (λa. if a < IArray.length A then A !! a else 0) i -
(λa. if a < IArray.length B then B !! a else 0) i"
using of_fun_nth[of i "(max (IArray.length A) (IArray.length B))"] using iB by simp
also have "...= A!!i - B !! i" using iA iB by simp
finally show "IArray.of_fun
(λa. IArray.of_fun (λa. if a < IArray.length A then A !! a else 0) (max (IArray.length A) (IArray.length B)) !! a -
IArray.of_fun (λa. if a < IArray.length B then B !! a else 0) (max (IArray.length A) (IArray.length B)) !! a)
(max (IArray.length A) (IArray.length B)) !! i = A !! i - B !! i" .
qed
lemma length_plus_iarray:
"IArray.length (A+B)=max (IArray.length A) (IArray.length B)"
unfolding plus_iarray_def Let_def by auto
lemma length_sum_iarray:
assumes "finite S" and "S≠{}"
shows "IArray.length (sum f S) = Max {IArray.length (f x)| x. x ∈ S}"
using assms
proof (induct S,simp)
case (insert x F)
show?case
proof (cases "F={}")
case True show ?thesis unfolding True by auto
next
case False
have rw: "IArray.length (sum f F) = Max {IArray.length (f x) |x. x ∈ F}"
by (rule insert.hyps, simp add: False)
have set_rw: "(insert (IArray.length (f x)) {IArray.length (f x) |x. x ∈ F}) = {IArray.length (f a) |a. a ∈ insert x F}"
by auto
have "IArray.length (sum f (insert x F)) = IArray.length (f x + sum f F)"
by (metis insert.hyps(1) insert.hyps(2) sum_clauses(2))
also have "... = max (IArray.length (f x)) (IArray.length (sum f F))"
unfolding length_plus_iarray ..
also have "... = max (IArray.length (f x)) (Max {IArray.length (f a) |a. a ∈ F})" unfolding rw by simp
also have "... = Max (insert (IArray.length (f x)) {IArray.length (f a) |a. a ∈ F})"
proof(rule Max_insert[symmetric])
show "finite {IArray.length (f x) |x. x ∈ F}" using insert.hyps(1) by auto
show "{IArray.length (f x) |x. x ∈ F} ≠ {}" by (metis (lifting, mono_tags) False empty_Collect_eq ex_in_conv)
qed
also have "...= Max {IArray.length (f a) |a. a ∈ insert x F}" unfolding set_rw ..
finally show ?thesis .
qed
qed
lemma sum_component_iarray:
assumes a: "∀x∈S. i<IArray.length (f x)"
and f: "finite S"
and S: "S≠{}"
shows "sum f S !! i = (∑x∈S. f x !! i)"
using f a S
proof (induct S, simp)
case (insert x F)
have finite_F: "finite F" by (metis insert.hyps(1))
show ?case
proof (cases "F={}")
case True
have "sum f (insert x F) !! i = f x !! i" unfolding True by auto
also have "... = (∑x∈insert x F. f x !! i)" unfolding True by auto
finally show ?thesis .
next
case False
have hyp: "(sum f F !! i)=(∑x∈F. f x !! i)"
proof (rule insert.hyps)
show "∀x∈F. i < IArray.length (f x)" by (metis insert.prems(1) insertCI)
show "F ≠ {}" using False .
qed
have "sum f (insert x F) !! i = (f x + sum f F) !! i"
by (metis insert.hyps(1) insert.hyps(2) sum_clauses(2))
also have "... = (f x) !! i + (sum f F !! i)"
proof (rule plus_iarray_component)
obtain a where a: "a∈F" using False by auto
have finite_C: "finite {IArray.length (f x) |x. x ∈ F}" using finite_F by auto
have not_empty_C: "{IArray.length (f x) |x. x ∈ F} ≠{}" using False by simp
show "i < IArray.length (f x)" by (metis insert.prems(1) insertI1)
show "i < IArray.length (sum f F)"
unfolding length_sum_iarray[OF finite_F False]
unfolding Max_gr_iff[OF finite_C not_empty_C]
proof (rule bexI[of _ "IArray.length (f a)"])
show "i < IArray.length (f a)" using insert.prems(1) a by auto
show "IArray.length (f a) ∈ {IArray.length (f x) |x. x ∈ F}" using a by auto
qed
qed
also have "...= (f x) !! i + (∑x∈F. f x !! i)" unfolding hyp ..
also have "...= (∑x∈insert x F. f x !! i)"
by (metis (mono_tags) insert.hyps(1) insert.hyps(2) sum_clauses(2))
finally show "sum f (insert x F) !! i = (∑x∈insert x F. f x !! i)" .
qed
qed
lemma length_zero_iarray: "IArray.length 0 = 0"
unfolding zero_iarray_def by simp
lemma minus_zero_iarray:
fixes A::"'a::{group_add} iarray"
shows "A - 0 = A"
proof (unfold iarray_exhaust2 list_eq_iff_nth_eq, auto, unfold IArray.length_def[symmetric] IArray.sub_def[symmetric])
have max_eq: "(max (IArray.length A) (IArray.length 0))= IArray.length A"
unfolding zero_iarray_def by auto
show length_eq: "IArray.length (A - 0) = IArray.length A"
unfolding minus_iarray_def Let_def unfolding max_eq by auto
fix i assume i: "i < IArray.length (A - 0)"
hence i2: "i< (IArray.length A)" unfolding length_eq .
have "A - 0 = IArray.of_fun
(λa. IArray.of_fun (λa. if a < IArray.length A then A !! a else 0) (IArray.length A) !! a -
IArray.of_fun (λa. if a < IArray.length (0::'a iarray) then 0 !! a else 0) (IArray.length A) !! a)
(IArray.length A)"
unfolding minus_iarray_def Let_def unfolding max_eq ..
also have "... !! i = A !! i" unfolding of_fun_nth[OF i2] length_zero_iarray using i2 by auto
finally show "(A - 0) !! i = A !! i" .
qed
subsection‹Inner mult over real iarrays›
definition inner_iarray :: "real iarray => real iarray => real" (infixl "∙i" 70)
where "inner_iarray A B = sum (λn. A !! n * B !! n) {0..<IArray.length A}"
lemma vec_to_iarray_inner:
"a ∙ b = vec_to_iarray a ∙i vec_to_iarray b"
proof (unfold inner_iarray_def inner_vec_def, auto, unfold IArray.sub_def[symmetric] IArray.length_def[symmetric])
have set_rw: "{0..<IArray.length (vec_to_iarray a)} = (to_nat)`(UNIV::'a set)"
unfolding vec_to_iarray_def
using to_nat_less_card using bij_to_nat[where ?'a='a]
unfolding bij_betw_def by auto
have inj: "inj_on (to_nat::'a=>nat) (UNIV::'a set)"
by (metis strict_mono_imp_inj_on strict_mono_to_nat)
have "(∑n = 0..<IArray.length (vec_to_iarray a). vec_to_iarray a !! n * vec_to_iarray b !! n)
= (∑n∈range (to_nat::'a=>nat). vec_to_iarray a !! n * vec_to_iarray b !! n)"
unfolding set_rw ..
also have "... = (∑x∈(UNIV::'a set). vec_to_iarray a !! to_nat x * vec_to_iarray b !! to_nat x)"
unfolding sum.reindex[OF inj] o_def ..
also have "...= (∑x∈UNIV. a $ x * b $ x)" unfolding vec_to_iarray_nth' ..
finally show "(∑i∈UNIV. a $ i * b $ i)
= (∑n = 0..<IArray.length (vec_to_iarray a). vec_to_iarray a !! n * vec_to_iarray b !! n)" ..
qed
lemma vec_to_iarray_scaleR:
"vec_to_iarray (a *⇩R x) = a *⇩R (vec_to_iarray x)"
unfolding scaleR_vec_def scaleR_iarray_def vec_to_iarray_def by auto
subsection‹Gram Schmidt over IArrays›
definition "Gram_Schmidt_column_k_iarrays A k
= tabulate2 (nrows_iarray A) (ncols_iarray A) (λa b. (if b = k
then (column_iarray b A - sum (λx. (((column_iarray b A) ∙i x) / (x ∙i x)) *⇩R x)
(set (List.map (λn. column_iarray n A) [0..<b])))
else (column_iarray b A)) !! a)"
definition "Gram_Schmidt_upt_k_iarrays A k = List.foldl Gram_Schmidt_column_k_iarrays A [0..<(Suc k)]"
definition "Gram_Schmidt_matrix_iarrays A = Gram_Schmidt_upt_k_iarrays A (ncols_iarray A - 1)"
lemma matrix_to_iarray_Gram_Schmidt_column_k:
fixes A::"real^'cols::{mod_type}^'rows::{mod_type}"
assumes k: "k<ncols A"
shows "matrix_to_iarray (Gram_Schmidt_column_k A k) = Gram_Schmidt_column_k_iarrays (matrix_to_iarray A) k"
proof (unfold iarray_exhaust2 list_eq_iff_nth_eq, rule conjI, auto, unfold IArray.sub_def[symmetric] IArray.length_def[symmetric])
show "IArray.length (matrix_to_iarray (Gram_Schmidt_column_k A k)) = IArray.length (Gram_Schmidt_column_k_iarrays (matrix_to_iarray A) k)"
unfolding matrix_to_iarray_def Gram_Schmidt_column_k_iarrays_def tabulate2_def unfolding nrows_iarray_def by auto
fix i assume i: "i < IArray.length (matrix_to_iarray (Gram_Schmidt_column_k A k))"
show "IArray.length (matrix_to_iarray (Gram_Schmidt_column_k A k) !! i)
= IArray.length (Gram_Schmidt_column_k_iarrays (matrix_to_iarray A) k !! i)"
unfolding matrix_to_iarray_def Gram_Schmidt_column_k_iarrays_def tabulate2_def
unfolding nrows_iarray_def ncols_iarray_def o_def
proof (auto)
have f1: "i < card (UNIV::'rows set)"
by (metis i length_eq_card_rows)
have f2: "⋀x⇩5. IArray.list_of (vec_to_iarray x⇩5)
= List.map (λuua. x⇩5 $ (from_nat uua::'cols)::real) [0..<card (UNIV::'cols set)]"
by (metis list_of.simps IArray.of_fun_def vec_to_iarray_def)
thus "length (IArray.list_of (List.map (λx. vec_to_iarray (Gram_Schmidt_column_k A k $ from_nat x)) [0..<card (UNIV::'rows set)] ! i))
= length (IArray.list_of (List.map (λi. IArray (List.map (λb. IArray.list_of (if b = k then column_iarray b (IArray (List.map (λx. vec_to_iarray (A $ from_nat x)) [0..<card (UNIV::'rows set)]))
- (∑x∈set (List.map (λn. column_iarray n (IArray (List.map (λx. vec_to_iarray (A $ from_nat x)) [0..<card (UNIV::'rows set)]))) [0..< b]). (column_iarray b (IArray (List.map (λx. vec_to_iarray (A $ from_nat x)) [0..<card (UNIV::'rows set)])) ∙i x / (x ∙i x)) *⇩R x) else column_iarray b (IArray (List.map (λx. vec_to_iarray (A $ from_nat x)) [0..<card (UNIV::'rows set)]))) ! i) [0..< length (IArray.list_of (vec_to_iarray (A $ from_nat 0)))])) [0..<card (UNIV::'rows set)] ! i))"
using f1 by auto
qed
next
fix i ia
assume i: "i < IArray.length (matrix_to_iarray (Gram_Schmidt_column_k A k))"
and ia: "ia < IArray.length (matrix_to_iarray (Gram_Schmidt_column_k A k) !! i)"
have i_nrows: "i<nrows A" using i unfolding matrix_to_iarray_def nrows_def by auto
have ia_ncols: "ia<ncols A" using ia unfolding matrix_to_iarray_def o_def vec_to_iarray_def ncols_def
by (auto, metis (no_types) Ex_list_of_length i_nrows length_map list_of.simps map_nth nrows_def nth_map)
have i_nrows_iarray: "i<nrows_iarray (matrix_to_iarray A)" using i_nrows by (metis matrix_to_iarray_nrows)
have ia_ncols_iarray: "ia<ncols_iarray (matrix_to_iarray A)" using ia_ncols by (metis matrix_to_iarray_ncols)
show "matrix_to_iarray (Gram_Schmidt_column_k A k) !! i !! ia = Gram_Schmidt_column_k_iarrays (matrix_to_iarray A) k !! i !! ia"
unfolding Gram_Schmidt_column_k_def Gram_Schmidt_column_k_iarrays_def
unfolding matrix_to_iarray_nth[of _ "from_nat i::'rows" "from_nat ia::'cols",
unfolded to_nat_from_nat_id[OF i_nrows[unfolded nrows_def]]
to_nat_from_nat_id[OF ia_ncols[unfolded ncols_def]]]
unfolding tabulate2_def
unfolding of_fun_nth[OF i_nrows_iarray]
unfolding of_fun_nth[OF ia_ncols_iarray]
proof (unfold proj_onto_def proj_def[abs_def], auto, unfold IArray.sub_def[symmetric])
have inj: "inj_on vec_to_iarray {column i A |i. i < from_nat k}" unfolding inj_on_def
by (auto, metis vec_to_iarray_morph)
have set_rw: "{column i A |i. i < from_nat k} = (λn. column n A)` {0..<from_nat k}"
proof (unfold image_def, auto)
fix a::'cols assume a: "a < from_nat k"
show "∃x∈{0..<from_nat k}. column a A = column x A"
by (rule bexI[of _ a], auto simp add: a least_mod_type)
qed
have set_rw2: "vec_to_iarray` {column i A |i. i < from_nat k}
= (λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}"
proof (unfold image_def, auto)
fix a::'cols assume a: "a < from_nat k"
show "∃x∈{0..<k}. vec_to_iarray (column a A) = column_iarray x (matrix_to_iarray A)"
by (rule bexI[of _ "to_nat a"], auto simp add: a to_nat_le vec_to_iarray_column)
next
fix xa assume xa: "xa < k"
have xa': "(from_nat xa::'cols) < from_nat k" by (rule from_nat_mono[OF xa k[unfolded ncols_def]])
show "∃x. (∃i. x = column i A ∧ i < from_nat k) ∧ column_iarray xa (matrix_to_iarray A) = vec_to_iarray x"
apply (rule exI[of _ "column (from_nat xa) A"])
apply auto apply (rule exI[of _ "from_nat xa"])
apply (auto simp add: xa' vec_to_iarray_column)
by (metis k order.strict_trans vec_to_iarray_column vec_to_iarray_column' xa)
qed
show "column (from_nat k) A $ from_nat i -
(∑x∈{column i A |i. i < from_nat k}. column (from_nat k) A ∙ x * x $ from_nat i / (x ∙ x)) =
(column_iarray k (matrix_to_iarray A) -
(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x)) !! i"
proof (cases "k=0")
case True
have set_rw_empty: "{column i A |i. i < from_nat k}={}"
unfolding True from_nat_0 using least_mod_type not_le by auto
have "column (from_nat k) A $ from_nat i -
(∑x∈{column i A |i. i < from_nat k}. column (from_nat k) A ∙ x
* x $ from_nat i / (x ∙ x)) =
column (from_nat k) A $ from_nat i - 0" unfolding set_rw_empty by simp
also have "...= column (from_nat k) A $ from_nat i" by simp
also have "...= (column_iarray k (matrix_to_iarray A) - 0) !! i"
unfolding minus_zero_iarray
unfolding vec_to_iarray_column'[OF k, symmetric]
unfolding vec_to_iarray_nth[OF i_nrows[unfolded nrows_def]] ..
also have "...= (column_iarray k (matrix_to_iarray A) -
(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x))
!! i" unfolding True by auto
finally show ?thesis .
next
case False
have "(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x/ (x ∙i x)) *⇩R x) !! i =
(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}.
(( column_iarray k (matrix_to_iarray A) ∙i x/ (x ∙i x)) *⇩R x) !! i)"
proof (rule sum_component_iarray)
show "∀x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. i < IArray.length ((column_iarray k (matrix_to_iarray A) ∙i x/ (x ∙i x)) *⇩R x)"
proof (unfold column_iarray_def, auto)
fix x :: nat
have "i < length (IArray.list_of (IArray (map (vec_to_iarray ∘ ($) A ∘ mod_type_class.from_nat) [0..<card (UNIV::'rows set)])))"
by (metis i_nrows_iarray IArray.length_def matrix_to_iarray_def nrows_iarray_def)
thus "i < length (IArray.list_of ((IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! k) [0..<length (IArray.list_of (matrix_to_iarray A))]) ∙i IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! x) [0..<length (IArray.list_of (matrix_to_iarray A))]) / (IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! x) [0..<length (IArray.list_of (matrix_to_iarray A))]) ∙i IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! x) [0..<length (IArray.list_of (matrix_to_iarray A))]))) *⇩R IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! x) [0..<length (IArray.list_of (matrix_to_iarray A))])))"
by (simp add: matrix_to_iarray_def scaleR_iarray_def)
qed
show "finite ((λn. column_iarray n (matrix_to_iarray A)) ` {0..<k})" by auto
show "(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k} ≠ {}" using False by auto
qed
also have "... = (∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}.
(column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x !! i)"
proof (rule sum.cong)
fix x assume "x ∈ (λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}"
from this obtain n where x: "x = column_iarray n (matrix_to_iarray A)" and n: "n<k" by auto
have n_ncols: "n<ncols A" by (metis k n order.strict_trans)
have c_eq: "column_iarray k (matrix_to_iarray A) = vec_to_iarray (column (from_nat k::'cols) A)"
by (metis k vec_to_iarray_column')
show "((column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x) !! i
= (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x !! i"
unfolding x
unfolding vec_to_iarray_column[symmetric, of "from_nat n::'cols",
unfolded to_nat_from_nat_id[OF n_ncols[unfolded ncols_def]]]
unfolding c_eq
unfolding vec_to_iarray_inner[symmetric]
unfolding vec_to_iarray_nth[OF i_nrows[unfolded nrows_def]]
unfolding vector_scaleR_component[symmetric]
unfolding vec_to_iarray_nth'[symmetric]
unfolding to_nat_from_nat_id[OF i_nrows[unfolded nrows_def]]
unfolding vec_to_iarray_scaleR ..
qed (simp)
also have "... = (∑x∈vec_to_iarray ` {column i A |i. i < from_nat k}. (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x !! i)"
unfolding set_rw2[symmetric] ..
also have "...=
(∑x∈{column i A |i. i < from_nat k}. (column (from_nat k) A ∙ x / (x ∙ x)) *⇩R vec_to_iarray x !! i)"
unfolding sum.reindex[OF inj] o_def
unfolding vec_to_iarray_column[of "from_nat k::'cols",symmetric,unfolded to_nat_from_nat_id[OF k[unfolded ncols_def]]]
unfolding vec_to_iarray_inner[symmetric] ..
also have "...
= (∑x∈{column i A |i. i < from_nat k}. column (from_nat k) A ∙ x * x $ from_nat i / (x ∙ x))"
unfolding vec_to_iarray_nth[OF i_nrows[unfolded nrows_def]] by auto
finally have *: "(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x) !! i
= (∑x∈{column i A |i. i < from_nat k}. column (from_nat k) A ∙ x * x $ from_nat i / (x ∙ x))" .
have "(column_iarray k (matrix_to_iarray A) -
(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x)) !! i =
(column_iarray k (matrix_to_iarray A) !! i -
(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x) !! i)"
proof (rule minus_iarray_component)
have finite: "finite ((λn. column_iarray n (matrix_to_iarray A)) ` {0..<k})"
using False by auto
have not_empty: "(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k} ≠ {}"
by (metis False atLeastLessThan_empty_iff2 empty_is_image neq0_conv)
let ?C="{IArray.length ((column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x) |x. x ∈ (λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}}"
have finite_C: "finite ?C" by auto
have not_empty_C: "?C ≠ {}" using False by auto
let ?x="(column_iarray 0 (matrix_to_iarray A))"
let ?c="IArray.length ((column_iarray k (matrix_to_iarray A) ∙i ?x / (?x ∙i ?x)) *⇩R ?x)"
show "i < IArray.length (column_iarray k (matrix_to_iarray A))"
unfolding column_iarray_def
by (auto, metis i_nrows_iarray IArray.length_def nrows_iarray_def)
show "i < IArray.length (∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x)"
unfolding length_sum_iarray[OF finite not_empty]
unfolding Max_gr_iff[OF finite_C not_empty_C]
proof (rule bexI[of _ "?c"])
show "i < ?c"
proof (unfold column_iarray_def, auto)
have "i < card (UNIV::'rows set)"
by (metis (no_types) i_nrows nrows_def)
thus "i < length (IArray.list_of ((IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! k) [0..<length (IArray.list_of (matrix_to_iarray A))]) ∙i IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! 0) [0..<length (IArray.list_of (matrix_to_iarray A))]) / (IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! 0) [0..<length (IArray.list_of (matrix_to_iarray A))]) ∙i IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! 0) [0..<length (IArray.list_of (matrix_to_iarray A))]))) *⇩R IArray (map (λn. IArray.list_of (IArray.list_of (matrix_to_iarray A) ! n) ! 0) [0..<length (IArray.list_of (matrix_to_iarray A))])))"
by (simp add: matrix_to_iarray_def scaleR_iarray_def)
qed
show "?c ∈ {IArray.length ((column_iarray k (matrix_to_iarray A) ∙i x / (x ∙i x)) *⇩R x)
|x. x ∈ (λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}}"
using False by auto
qed
qed
also have "... = column_iarray k (matrix_to_iarray A) !! i -
(∑x∈{column i A |i. i < from_nat k}. column (from_nat k) A ∙ x * x $ from_nat i / (x ∙ x))"
unfolding * ..
also have "... = column (from_nat k) A $ from_nat i -
(∑x∈{column i A |i. i < from_nat k}. column (from_nat k) A ∙ x * x $ from_nat i / (x ∙ x))"
unfolding vec_to_iarray_column[of "from_nat k::'cols",symmetric,unfolded to_nat_from_nat_id[OF k[unfolded ncols_def]]]
unfolding vec_to_iarray_nth[OF i_nrows[unfolded nrows_def]] ..
finally show "column (from_nat k) A $ from_nat i -
(∑x∈{column i A |i. i < from_nat k}. column (from_nat k) A ∙ x * x $ from_nat i / (x ∙ x)) =
(column_iarray k (matrix_to_iarray A) -
(∑x∈(λn. column_iarray n (matrix_to_iarray A)) ` {0..<k}. (column_iarray k (matrix_to_iarray A) ∙i x/ (x ∙i x)) *⇩R x)) !! i"
..
qed
show "column (from_nat ia) A $ from_nat i = column_iarray ia (matrix_to_iarray A) !! i"
unfolding vec_to_iarray_nth[symmetric, OF i_nrows[unfolded nrows_def]]
unfolding vec_to_iarray_column'[symmetric, OF ia_ncols] ..
assume ia_not_k: "ia ≠ k"
and eq: "from_nat ia = (from_nat k::'cols)"
have "ia=k" by (rule from_nat_eq_imp_eq[OF eq ia_ncols[unfolded ncols_def] k[unfolded ncols_def]])
thus "column (from_nat k) A $ from_nat i
- (∑x∈{column i A |i. i < from_nat k}.
column (from_nat k) A ∙ x * x $ from_nat i / (x ∙ x))
= column_iarray ia (matrix_to_iarray A) !! i"
using ia_not_k by contradiction
qed
qed
lemma matrix_to_iarray_Gram_Schmidt_upt_k:
fixes A::"real^'cols::{mod_type}^'rows::{mod_type}"
assumes k: "k<ncols A"
shows "matrix_to_iarray (Gram_Schmidt_upt_k A k) = Gram_Schmidt_upt_k_iarrays (matrix_to_iarray A) k"
using k
proof (induct k)
case 0
show ?case unfolding Gram_Schmidt_upt_k_def Gram_Schmidt_upt_k_iarrays_def
by (simp add: matrix_to_iarray_Gram_Schmidt_column_k[OF "0.prems"])
next
case (Suc k)
have k: "k<ncols (Gram_Schmidt_upt_k A k)" using Suc.prems unfolding ncols_def by simp
have k2: "Suc k < ncols (Gram_Schmidt_upt_k A k)" using Suc.prems unfolding ncols_def .
have list_rw: "[0..<Suc (Suc k)] = [0..<Suc k] @ [(Suc k)]" by simp
have hyp: "matrix_to_iarray (Gram_Schmidt_upt_k A k) = Gram_Schmidt_upt_k_iarrays (matrix_to_iarray A) k"
by (metis Suc.hyps Suc.prems Suc_lessD)
show "matrix_to_iarray (Gram_Schmidt_upt_k A (Suc k)) = Gram_Schmidt_upt_k_iarrays (matrix_to_iarray A) (Suc k)"
unfolding Gram_Schmidt_upt_k_def Gram_Schmidt_upt_k_iarrays_def
unfolding list_rw
unfolding foldl_append
unfolding foldl.simps
unfolding Gram_Schmidt_upt_k_def[symmetric] Gram_Schmidt_upt_k_iarrays_def[symmetric]
unfolding hyp[symmetric]
by (rule matrix_to_iarray_Gram_Schmidt_column_k[OF k2])
qed
lemma matrix_to_iarray_Gram_Schmidt_matrix[code_unfold]:
fixes A::"real^'cols::{mod_type}^'rows::{mod_type}"
shows "matrix_to_iarray (Gram_Schmidt_matrix A) = Gram_Schmidt_matrix_iarrays (matrix_to_iarray A)"
unfolding Gram_Schmidt_matrix_def Gram_Schmidt_matrix_iarrays_def
unfolding matrix_to_iarray_ncols[symmetric]
by (rule matrix_to_iarray_Gram_Schmidt_upt_k, simp add: ncols_def)
text‹Examples:›
value"let A = list_of_list_to_matrix [[4,5],[8,1],[-1,5]]::real^2^3
in iarray_of_iarray_to_list_of_list (matrix_to_iarray (Gram_Schmidt_matrix A))"
value "let A = IArray[IArray[4,5],IArray[8,1],IArray[-1,5]]
in iarray_of_iarray_to_list_of_list (Gram_Schmidt_matrix_iarrays A)"
end