using linear interpolation to find coefficients

Hi, i want to create a function that interpolates linearly to give me the coefficients. As an example, the function must take in AerodynamicData.Cm.BodyFlap (see below) and must use VehicleState to find the interpolated value of CmBodyFlap, which is the contribution that the body flap makes towards the aerodynamic coefficient named, Cm.

AerodynamicData.Cm.BodyFlap =

struct with fields:

deBF: [-11.7000 -5 0 5 10 16.3000 22.5000]

alpha: [-10 -5 0 5 10 15 20 25 30 35 40 45 50]

CmBodyFlap: [7×13 double]

VehicleState =

struct with fields:

alpha: 40

Mach: 5

deBF: 6

deSB: 0

deA: 0

Please help.

Answer 1

[Sulaymon Eshkabilov]

Hi,

use polyfit(); e.g.

x = alpha; y = deBF; % then

Coeff= polyfit(x, y, N); % N=1 linear fit, N=2 second order polynomial fit, N=3 cubic polynomial, etc.

[madhan ravi]

Please use the code button.

Answer 2

[David Hill]

Make sure your matrix agrees with the meshgrid generated or change it to match.

[d,a]=meshgrid(AerodynamicData.Cm.BodyFlap.deBF,AerodynamicData.Cm.BodyFlap.alpha);
CmBodyFlap_interp=interp2(d,a,AerodynamicData.Cm.BodyFlap.CmBodyFlap,VehicleState.deBF,VehicleState.alpha);