Question
Hi, I want to plot a line passing through a set of points, which is as in the code below. To determine the slope I used polyfit. But it gives two outputs. I wonder which output I should consider out of the two outputs it is giving me? clc; clear; phi_1 = [0.1724*pi 0.1472*pi 2.18*pi 2.25*pi 4*pi 3.588*pi 1.012*pi 4.112*pi 4.31*pi 4.25*pi 0.832*pi]; x1 = linspace(0,1,11); figure(1) plot(x1,phi_1,'o'); coefficients1=polyfit(x1,phi_1,1) slope1=coefficients1(1); coefficients1=polyfit(x1,phi_1,1) coefficients1 = 1×2 7.6641 3.8373 slope1=coefficients1(1);
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Expert Answer
Neeta Dsouza
PhD Expert
Answered Nov 20, 2025
The first line of the function description on the documentation for polyfit states precisely what those outputs are.
They are the coefficients of the descending powers of the fitted polynomial. You asked for a 1st-order polynomial, so the first element of the output is the coefficient of the linear (1st-order) term, and the second element of the output is the coefficient of the intercept (the 0th-order term).
clc; clear; phi_1 = [0.1724*pi 0.1472*pi 2.18*pi 2.25*pi 4*pi 3.588*pi 1.012*pi 4.112*pi 4.31*pi 4.25*pi 0.832*pi]; x1 = linspace(0,1,11); coefficients1=polyfit(x1,phi_1,1)
coefficients1 = 1×2
7.6641 3.8373
slope1=coefficients1(1); intercept1=coefficients1(2)
intercept1 = 3.8373
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