# How to fit a model a=bx+cy form, for series of data?

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Annu Panwar on 23 Jun 2017
Answered: Bernhard Suhm on 6 Dec 2017
a=[3, 4, 6, 7,8] b=[5,9,10,12,19] a=[3,4,5,6,7,9]
x and y are known how to get the value of x and y using linear fit? I can solve the equations and get the value but I want only one values for x and y. Please provide help?
Hendrik on 27 Nov 2017
the last a should be c??? If yes what about the dimensions? dim(a & b) = [1,5]; dim(a'' =?c) = [1,6];

Bernhard Suhm on 6 Dec 2017
If you interpret a=bx+cy as a linear equation with the scalars x,y as unknown (even though you said they are known), it's an overconstrained system of linear equations and there is no solution - but you probably knew that.
If you interpret your vectors to specify a set of datapoints, with a as the 'response' and b and c as the predictors, you can force MATLAB to fit a linear model with tbl = table(c',b',a','VariableNames',{'c','b','a'}); lm = fitlm(tbl,'a~b+c','Intercept','false');
Note that I transposed your row vectors into columns to build the data table ("frame").

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