clear;clf

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%?Higham?J.E.?Brevis?W?&?Keylock?C.J.?（2018）?
%?Implications?of?the?selection?of?a?particular?modal?decomposition?technique?for?the?analysis?of?shallow?flows?
%?Journal?of?Hydraulic?Research
%?Taylor?and?Francis
%?10.1080/00221686.2017.1419990?
%?Any?questions?email?jonny.e.higham@gmail.com

%%%%%%%%%%%%%%%%%%%?USAGE?%%%%%%%%%%%%%%%%%%%%%%

%?When?the?data?is?input?the?POD?modes?will?be?calculated?after?which?you
%?are?promped?with?a?window?to?choose?the?frequency?highlighted?in?the
%?particular?POD?mode?which?you?would?like?the?DMD?algorithm?to?extract.?

%%%%%%%%%%%%%%%%%%?EXAMPLES?%%%%%%%%%%%%%%%%%%%%

%?Here?we?provide?two?examples?‘cylinder‘?&?‘groyne‘?change?by?either?using
%?‘cylinder‘?or?‘groyne‘;
%?Chose?the?cylinder?example?for?one?velocity?component?and?the?groyne?for
%?two?velocity?components?（this?can?easily?be?extended?to?three?components

%%%%%%%%%%%%%%%%%%??INPUT??%%%%%%%%%%%%%%%%%%%%%

freq?=?5;?%Hz;?aquisition?frequency
example?=?‘cylinder‘;?%?input?case?（cylinder?/?groyne）?
mode=2;?%?which?mode?to?plot?and?extract?DMD?from

%%%%%%%%%%%%%%%%%%%?script?%%%%%%%%%%%%%%%%%%%%%

%?Import?the?images?from?folder.?The?colour?images?are?converted?to
%?grayscale.?
data?=?[];
if?strcmp（example‘cylinder‘）
????directory?=?‘data_cylinder‘;
????count?=?1;
????while?exist（sprintf（‘%s/B_%0.4d.bmp‘directorycount））?~=?0????%?exist?檢驗變量或文件是否存在??sprintf?格式化輸出
????????data（::count）?=?imread（sprintf（‘%s/B_%0.4d.bmp‘directorycount））;?%?imread?圖像讀入
????????count?=?count?+1;
????end

????r?=?size（data1）;?c?=?size（data2）;
????%?Transform?the?data?into?column?vectors.
????data=reshape（datar*csize（data3））;????%??data?重構出?r*c?X?size（data3）的?矩陣
end
if?strcmp（example‘groynes‘）
????directory?=?‘data_groynes‘;
????count?=?1;
????while?exist（sprintf（‘%s/PIV_%0.4d.mat‘directorycount））?~=?0
????????load（sprintf（‘%s/PIV_%0.4d.mat‘directorycount））
????????data_u（::count）?=?u;
????????data_v（::count）?=?v;
????????count?=?count?+1;
????end
????r?=?size（data_u1）;?c?=?size（data_u2）;
????%?Transform?the?data?into?column?vectors.
????data=[reshape（data_ur*csize（data_u3））;reshape（data_vr*csize（data_v3））];
end

%%%%%%%%%%%%%%%%%%%?POD?%%%%%%%%%%%%%%%%%%%%%%

%?Perform?the?POD?-?this?is?mean?subtracted?for?POD?not?for?DMD
[Phi?~?C]=svd（data-repmat（mean（data2）?[1?size（data2）]）‘econ‘）;??%?repmat?復制平鋪矩陣??mean（data2）為行平均的列向量
??????????????????????????????????????????????????????????????????????%?奇異值分解（精簡分解）
????????????