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Population and profit using linear regression

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Yeasir Mohammad Akib
回答： Star Strider 2015-9-8
Suppose there are 97 data sets .I have to compute the cost using linear regression .I am calling the data from a txt. file .
function J = computeCost(X, y, theta)
J=0;m = length(y);
data=load('ex1data1.txt');
x=data(:,1);y=data(:,2);
h=X*theta;
error=h-y;
error_sqr=(h-y).^2;
J=(1/(2*m))*(sum(error_sqr));
If I use the following code in command window then the following results is shown.What is the problem with the code ?
computeCost(ones(m, 1), data(:,1),data(:,2),zeros(2, 1))
Undefined function or variable 'm'.

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Star Strider
Star Strider 2015-9-8
This line is in your main (or calling) script, and you likely have not yet defined ‘m’ in it so that ‘m’ is a variable in the main script workspace:
computeCost(ones(m, 1), data(:,1),data(:,2),zeros(2, 1))
If ‘m’ is first defined in the function, it is local to that function, not to the main script workspace.

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