sir i have a sinosoidal signal and i want to fit the curve which cover the maximum data of that by using polyfit or polyval instruction how can i...????

a = [0 -1.43061558801942 0.449553769638651 0.563052881824671 0.363537935922275 -2.28756758511472 -2.50357386946423 2.45670867493125 0.736842277715324 -0.299156918582553 -1.75540037385161 -2.79669516937493 -0.971720745073923 1.37255636093699 -0.0290079071439933 2.08934318334818 -1.42051382069485 -0.814504230177740 -0.524025208712882 0.482095001546964 0.525768700476486 2.88990062408454 1.46331243352935 -2.01196953374551 1.00986418982086 -0.367421904619802 0.0861523640802418 -1.16560335109761 1.54038555516689 0.628936203561307 -1.23174384730983 0.366243532626739 0.0703495321510657 2.35750626082822 1.33190490985333 1.20560659136848 -1.80854560120597 -0.473883277855066 0.473883277855066 1.80854560120597 -1.20560659136848 -1.33190490985333 -2.35750626082822 -0.0703495321510657 -0.366243532626739 1.23174384730983 -0.628936203561307 -1.54038555516689 1.16560335109761 -0.0861523640802418 0.367421904619802 -1.00986418982086 2.01196953374551 -1.46331243352935 -2.88990062408454 -0.525768700476486 -0.482095001546964 0.524025208712882 0.814504230177740 1.42051382069485 -2.08934318334818 0.0290079071439933 -1.37255636093699 0.971720745073923 2.79669516937493 1.75540037385161 0.299156918582553 -0.736842277715324 -2.45670867493125 2.50357386946423 2.28756758511472 -0.363537935922275 -0.563052881824671 -0.449553769638651 1.43061558801942]

Answer 1

[Star Strider]

I would not use polyfit. You can fit it with core MATLAB functions and get all the relevant parameter estimates using the techniques in Curve Fitting To a Sinusoidal Function.