matlab第二章數(shù)值數(shù)組及其運(yùn)算(已改無(wú)錯(cuò)字)
2022-10-03 13:37:10 本頁(yè)面
【正文】 3)。A(:,:,2)=ones(2,3)*2。A(:,:,3)=ones(2,3)*3 A(:,:,1) = 1 1 1 1 1 1 A(:,:,2) = 2 2 2 2 2 2 A(:,:,3) = 3 3 3 3 3 3 【例 】由函數(shù) ones, zeros, rand, randn直接創(chuàng)建標(biāo)準(zhǔn)高維數(shù)組的示例。 rand(39。state39。,1111),rand(2,4,3) ans(:,:,1) = ans(:,:,2) = ans(:,:,3) = 【例 】借助 cat, repmat, reshape等函數(shù)構(gòu)作高維數(shù)組。 （ 1） cat(3,ones(2,3),ones(2,3)*2,ones(2,3)*3) ans(:,:,1) = 1 1 1 1 1 1 ans(:,:,2) = 2 2 2 2 2 2 ans(:,:,3) = 3 3 3 3 3 3 （ 2） repmat(ones(2,3),[1,1,3]) ans(:,:,1) = 1 1 1 14 1 1 1 ans(:,:,2) = 1 1 1 1 1 1 ans(:,:,3) = 1 1 1 1 1 1 （ 3） reshape(1:12,2,2,3) ans(:,:,1) = 1 3 2 4 ans(:,:,2) = 5 7 6 8 ans(:,:,3) = 9 11 10 12 高維數(shù)組的標(biāo)識(shí) 【例 】維數(shù)、大小和長(zhǎng)度 clear。A=reshape(1:24,2,3,4)。 dim_A=ndims(A) size_A=size(A) L_A=length(A) dim_A = 3 size_A = 2 3 4 L_A = 4 高維數(shù)組構(gòu)作和操作函數(shù)匯總 【例 】數(shù)組元素對(duì)稱(chēng)交換指令 flipdim的使用示例。 A=reshape(1:18,2,3,3) A(:,:,1) = 1 3 5 2 4 6 A(:,:,2) = 7 9 11 8 10 12 A(:,:,3) = 13 15 17 14 16 18 flipdim(A,1) ans(:,:,1) = 2 4 6 1 3 5 ans(:,:,2) = 15 8 10 12 7 9 11 ans(:,:,3) = 14 16 18 13 15 17 flipdim(A,3) ans(:,:,1) = 13 15 17 14 16 18 ans(:,:,2) = 7 9 11 8 10 12 ans(:,:,3) = 1 3 5 2 4 6 【例 】數(shù)組的“維序號(hào)左移”重組。 shiftdim(A,1) ans(:,:,1) = 1 7 13 3 9 15 5 11 17 ans(:,:,2) = 2 8 14 4 10 16 6 12 18 shiftdim(A,2) ans(:,:,1) = 1 2 7 8 13 14 ans(:,:,2) = 3 4 9 10 15 16 ans(:,:,3) = 5 6 11 12 17 18 【例 】廣義非共軛轉(zhuǎn)置。 permute(A,[2,3,1]) ans(:,:,1) = 1 7 13 3 9 15 5 11 17 ans(:,:,2) = 2 8 14 4 10 16 6 12 18 permute(A,[1,3,2]) ans(:,:,1) = 16 1 7 13 2 8 14 ans(:,:,2) = 3 9 15 4 10 16 ans(:,:,3) = 5 11 17 6 12 18 【例 】“孤維”的撤消和降維。 B=cat(4,A(:,:,1),A(:,:,2),A(:,:,3)) B(:,:,1,1) = 1 3 5 2 4 6 B(:,:,1,2) = 7 9 11 8 10 12 B(:,:,1,3) = 13 15 17 14 16 18 size(B) ans = 2 3 1 3 C=squeeze(B) C(:,:,1) = 1 3 5 2 4 6 C(:,:,2) = 7 9 11 8 10 12 C(:,:,3) = 13 15 17 14 16 18 size(C) ans = 2 3 3 【例 】賦“空陣”值操作。 A=reshape(1:18,2,3,3) A(:,:,1) = 1 3 5 2 4 6 A(:,:,2) = 7 9 11 8 10 12 A(:,:,3) = 13 15 17 14 16 18 A(:,2:3,:)=[] B=A。 A(:,:,1) = 17 1 2 A(:,:,2) = 7 8 A(:,:,3) = 13 14 size(A) ans = 2 1 3 A_1=squeeze(A) A_1 = 1 7 13 2 8 14 size(B) ans = 2 1 3 B(:,1,:)=[] B = Empty array: 2by0by3 “非數(shù)”和“空”數(shù)組 非數(shù) NaN 【例 】非數(shù)的產(chǎn)生和性質(zhì)演示。 （ 1） a=0/0,b=0*log(0),c=infinf
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