# Inner matrix dimensions must agree

조회 수: 2(최근 30일)
I wrote these codes, I splitted the dataset(colon attached) into two parts (data1 and data2) based on the last column(1 or else)and make the columns equal to each others.
clc;
clear;
close all;
tic
data=colon;
[n,m]=size(data);
d=10;
l=1;
t=1;
data1=[];
data2=[];
for i=1:n
if data(i,m)==1
data1(l,:)=data(i,1:m-1);
l=l+1;
else
data2(t,:)=data(i,1:m-1);
t=t+1;
end
end
if t>l
data1(l:t-1,1:m-1)=0;
else
data2(t:l-1,1:m-1)=0;
end
for i=1: m-1
thisCol1=data1(:,i);
thisCol2=data2(:,i);
a24(i)=fkumarjohnson(thisCol1,thisCol2);
end
and then in for loop I computed the distance value between the data1 and data2 and for computation I defined a function fkumarjohnson (I attached the image of the formula)but I found the error.
function [ fkj ] = fkumarjohnson(p,q )
%UNTITLED Summary of this function goes here
% Detailed explanation goes here
fkj=sum(((p*p-q*q).^2)/(2*(dot(p,q)).^(3/2)));
end
the error is:
Error using *
Inner matrix dimensions must agree.
Error in fkumarjohnson (line 4)
fkj=sum(((p*p-q*q).^2)/(2*(dot(p,q)).^(3/2)));
Error in myFSmethod (line 62)
a24(i)=fkumarjohnson(thisCol1,thisCol2);
The matlab said the inner matrix dimensions of two sides of * must agree but I don't know how to make their dimensions equal.I'll be very gratefull to have your opinions. Thanks

#### 댓글 수: 2

Stephen Cobeldick 10 Dec 2019
Are you sure that you want matrix multiplication?
Or do you actually need element-wise multiplication?
phdcomputer Eng 11 Dec 2019
@Stephen Cobeldick Thanks, I want to calculate the result of the formula, and I guess that the formula needs element wise multipication because I'm computing the distance between every column of the matrix (colon) so all the elements in a column(all instances) is involved in the formula calculations. For element wise multiplication these codes are right?

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### 채택된 답변

Fabio Freschi 10 Dec 2019
fkj= sum(.5*((p.^2-q.^2).^2)./((p.*q).^1.5));
Note that .^ .* and ./ operators are used for element-wise operation (see also Stephen's comment).
Note also that dot can give apparently unexpected results for complex inputs (see dot help)

#### 댓글 수: 4

표시 이전 댓글 수: 1
Fabio Freschi 11 Dec 2019
it is necessary to use element wise operators. you can leave the dot operator. But remember that for complex vectors, the dot product involves a complex conjugate and this could be not know to everyone.
phdcomputer Eng 11 Dec 2019
Thanks greatly.
phdcomputer Eng 11 Dec 2019
@Fabio Freschi Thanks greatly for your attention. the problem of the function in my question is solved by your advice, but for one function It has error:
function [ fkdg ] = fKDivergence( p,q )
fkdg=sum(p.*(log((2.*p)/(p+q))));
end
I used element-wise for several functions and their errors solved.
I used element-wise operator .* in the codes but MATLAB shows this error
Error using .*
Matrix dimensions must agree.
Error in fKDivergence (line 5)
fkdg=sum(p.*(log((2.*p)/(p+q))));
I'll be very gratefull to have your opinion. Thanks

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Image Analyst 11 Dec 2019
The error is described in the FAQ

#### 댓글 수: 3

phdcomputer Eng 11 Dec 2019
@ Image AnalystThanks, but I didn't understand how to use cell array to solve the problem.
Fabio Freschi 11 Dec 2019