Complete expression for matrix operator

Question

Madison 2023-7-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1997793-complete-expression-for-matrix-operator

编辑： Dyuman Joshi 2023-7-19

采纳的回答： Mrutyunjaya Hiremath

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When I change a paraenthesis to bracket I recieve an error, but when I use brackets I recieve another error

Parathesis:

File: untitled.m Line: 51 Column: 34

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or

other syntax error. To construct matrices, use brackets instead of parentheses.

Brackets:

% check this, which depth level do you want?
% Which is the surface and which is the bottom?
% are the layers a consistent depth?
% this info should be in some supporting document on CMEMS
depth=ncread(fullfile(fp,'June2021.nc'),'depth');
% change this depending on how many vertical levels you need to calculate
% if you want lots of depth layers you'll need to amend the loop below
% this is an example, pulling out the second depth layer
nz=2;
% change this to how many years you want to run this loop over
ystart=1972;
yend=2022;
nyear=yend-ystart+1
for yi=1:nyear
    ny=ystart+yi-1
    filename=[fullfile(fp,'June' num2str(ny) '.nc')];
Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.
    u1 = ncread(filename,'uo',[1 1 nz 1],[length(lon) length(lat) 1 ntime]);
    v1 = ncread(filename,'uo',[1 1 nz 1],[length(lon) length(lat) 1 ntime]);
    
    % if you want monthly averages, do this
    % note this will end up a different dimension if you're extracting
    % multiple layers
    % might want to predefine these matrices depending on what you want
    % https://uk.mathworks.com/help/matlab/ref/mean.html
    u2(:,:,yi)=mean(u1,[4]); whos u2
    v2(:,:,yi)=mean(v1,[4]);
    
end
% then take the mean to get the mean over all the years, for one depth
% layer only, remember
u3=mean(u2,[3]); %taking the mean over the third dimension
v3=mean(u2,[3]);
% calculate the magnitude of the vel and plot
uv4=sqrt(u3.^2+v3.^2);
close all, pcolor(LON,LAT,uv4.'), shading flat, colorbar

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Answer 1

Mrutyunjaya Hiremath 2023-7-19

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1997793-complete-expression-for-matrix-operator#answer_1275418

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use like this

filename= fullfile(fp,['June', num2str(ny), '.nc']);

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Madison 2023-7-19

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Thank you, I was able to fix this anwser, but recieved an error in the following line.

Error in untitled (line 52)

u1 = ncread(fullfile(filename,'uo',[1 1 nz 1],[length(lon) length(lat) 1 ntime]));

for yi=1:nyear
    ny=ystart+yi-1
    filename=fullfile(fp,['June' num2str(ny) '.nc']);
    u1 = ncread(fullfile(filename,'uo',[1 1 nz 1],[length(lon) length(lat) 1 ntime]));
    v1 = ncread(fullfilefilename,'uo',[1 1 nz 1],[length(lon) length(lat) 1 ntime]);
    
    % if you want monthly averages, do this
    % note this will end up a different dimension if you're extracting
    % multiple layers
    % might want to predefine these matrices depending on what you want
    % https://uk.mathworks.com/help/matlab/ref/mean.html
    u2(:,:,yi)=mean(u1,[4]); whos u2
    v2(:,:,yi)=mean(v1,[4]);
    
end
% then take the mean to get the mean over all the years, for one depth
% layer only, remember
u3=mean(u2,[3]); %taking the mean over the third dimension
v3=mean(u2,[3]);
% calculate the magnitude of the vel and plot
uv4=sqrt(u3.^2+v3.^2);
close all, pcolor(LON,LAT,uv4.'), shading flat, colorbar

Dyuman Joshi 2023-7-19

编辑：Dyuman Joshi 2023-7-19

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Please copy and paste the full error message i.e. all of the red text.

Also, you are missing a set of parenthesis in the definition of variable v1.

%                   v                                                          v
v1 = ncread(fullfile(filename,'uo',[1 1 nz 1],[length(lon) length(lat) 1 ntime]));

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