Hello everyone I'm new, can some help me little bit with my problem. I need to sum free Fourier together.

I tried like this first but it gives strange value.

clc;clearvars; close all;

step = 1;

x = 1:100

a0 = 2436;

a1 = -1008;

b1 = -4210;

a2 = -2692;

b2 = 1363;

a3 = 1037;

b3 = 1234;

a4 = 379;

b4 = -502;

a5 = -147.4;

b5 = -67.34;

a6 = -4.665;

b6 = 20.64;

w = 0.02518;

aa0 = -0.004139;

aa1 = 0.03085;

bb1 = 0.006164;

aa2 = -0.01731;

bb2 = 0.001776;

aa3 = 0.00198;

bb3 = 0.003651;

aa4 = -0.01478;

bb4 = -0.001275;

aa5 = 0.003926;

bb5 = 0.0005124;

aa6 = -0.008721;

bb6 = -0.004231;

ww = 0.06636;

aaa0 = 2.637e+05;

aaa1 = -3.116e+05;

bbb1 = -3.359e+05;

aaa2 = -2.211e+04;

bbb2 = 2.973e+05;

aaa3 = 1.105e+05;

bbb3 = -8.868e+04;

aaa4 = -4.626e+04;

bbb4 = -6556;

aaa5 = 5566;

bbb5 = 7825;

aaa6 = 171.1;

bbb6 = -915.6;

www = 0.01651;

S1 = a0 + a1*cos(x*w) + b1*sin(x*w) + a2*cos(2*x*w) + b2*sin(2*x*w) + a3*cos(3*x*w) + b3*sin(3*x*w) + a4*cos(4*x*w) + b4*sin(4*x*w) + a5*cos(5*x*w) + b5*sin(5*x*w) + a6*cos(6*x*w) + b6*sin(6*x*w);

S2 = aa0 + aa1*cos(x*ww) + bb1*sin(x*ww) + aa2*cos(2*x*ww) + bb2*sin(2*x*ww) + aa3*cos(3*x*ww) + bb3*sin(3*x*ww) + aa4*cos(4*x*ww) + bb4*sin(4*x*ww) + aa5*cos(5*x*ww) + bb5*sin(5*x*ww) + aa6*cos(6*x*ww) + bb6*sin(6*x*ww);

S3 = aaa0 + aaa1*cos(x*www) + bbb1*sin(x*www) + aaa2*cos(2*x*www) + bbb2*sin(2*x*www) + aaa3*cos(3*x*www) + bbb3*sin(3*x*www) + aaa4*cos(4*x*www) + bbb4*sin(4*x*www) + aaa5*cos(5*x*www) + bbb5*sin(5*x*www) + aaa6*cos(6*x*www) + bbb6*sin(6*x*www);

SS_n5 = S1 + S2 + S3;

plot(x, SS_n5, 'b-'); title('TEST')

I tried like this.

load enso;

x = 0:100;

f1 = fit(time,Test1,'fourier8')

f2 = fit(time,Test2,'fourier8')

f3 = fit(time,Test3,'fourier8')

SS=f1+f2+f3;

plot(x, SS, 'b-'); title('TEST');

But it gives error?

Undefined operator '+' for input arguments of type 'cfit'.

Error in Untitled5 (line 9)

SS=f2+f3;

Because workspace is not array.

Can someone help me with this?

How can I see later what coefficient in sum function?

Thanks in advance!!!

Answer 1

[Torsten]

x = 0:100;
F1 = feval(f1,x);
F2 = feval(f2,x);
F3 = feval(f3,x);
SS = F1 + F2 + F3;
plot(x,SS)

coefficientValues1 = coeffvalues(f1);
coefficientValues2 = coeffvalues(f2);
coefficientValues3 = coeffvalues(f3);
coefficientValues_SS = coefficientValues1 + coefficientValues2 + coefficientValues3

My question is: Why don't you fit f1+f2+f3 right from the beginning instead of doing this separately for f1,f2 and f3 ?

[Dmitri Ryybak]

Thank you for your fast answer. During the run I would like to plot the graphs separately. Because when I compared graphs in excel and matlab they was very different.

[Torsten]

Then

plot(x,F1)
hold on
plot(x,F2)
hold on
plot(x,F3)
hold on
plot(x,SS)

[Dmitri Ryybak]

Thank you for your answer. It seem starts to work. Can you please double check many code is it OK. Thank you in advance!

x = 0:100;

sample = [0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; ...

18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; ...

34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; ...

50; 51; 52; 53; 54; 55; 56; 57; 58; 59; 60; 61; 62; 63; 64; 65; ...

66; 67; 68; 69; 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; ...

82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93; 94; 95; 96; 97; ...

98; 99; 100];

Var1 = [0.0055; -0.0402; -0.0226; 0.0023; 0.0194; 0.0222; 0.0318; 0.0479; ...

0.0552; 0.0619; 0.0642; 0.0612; 0.0572; 0.052; 0.0448; 0.0377; ...

0.0312; 0.0295; 0.031; 0.0316; 0.029; 0.024; 0.0164; 0.0091; 0.0041; ...

0.0015; -0.0006; -0.0046; -0.0093; -0.0153; -0.0197; -0.0212; -0.0228; ...

-0.0237; -0.0253; -0.0264; -0.0266; -0.024; -0.0224; -0.0219; -0.0268; ...

-0.0349; -0.0432; -0.0537; -0.0633; -0.0709; -0.0768; -0.0825; ...

-0.0851; -0.0823; -0.0746; -0.0662; -0.0531; -0.0372; -0.0187; ...

-0.0058; 0.0009; 0.0024; 0.0023; 0.0019; 0.0011; 0.0002; -0.0005; ...

-0.001; -0.0009; -0.0005; 0.0001; 0.0007; 0.0011; 0.0013; 0.0013; ...

0.0012; 0.0011; 0.0011; 0.0012; 0.0013; 0.0014; 0.0015; 0.0015; ...

0.0016; 0.0016; 0.0016; 0.0014; 0.0011; 0.0007; 0.0002; -0.0004; ...

-0.0008; -0.0012; -0.0013; -0.0012; -0.0007; 0.0001; 0.0013; 0.003; ...

0.0049; 0.0069; 0.0086; 0.0104; 0.01; 0.01];

Var2 = [-0.0186; -0.5454; -0.0714; 0.1946; 0.1859; 0.2146; 0.3954; 0.5104; ...

0.5503; 0.5797; 0.5731; 0.5591; 0.5428; 0.5427; 0.5229; 0.4738; ...

0.4242; 0.3864; 0.3376; 0.2919; 0.2499; 0.2099; 0.1714; 0.1376; ...

0.1104; 0.0891; 0.0666; 0.0442; 0.0251; 0.0064; -0.0164; -0.035; ...

-0.0609; -0.0862; -0.1153; -0.1492; -0.1767; -0.2088; -0.2308; ...

-0.2627; -0.2698; -0.2981; -0.2963; -0.2884; -0.2835; -0.2607; ...

-0.2288; -0.1922; -0.1406; -0.0982; -0.0568; -0.0063; 0.0266; 0.0454; ...

0.043; 0.0376; 0.0296; 0.0169; 0.0154; 0.0137; 0.0117; 0.0089; ...

0.0051; 0.0002; -0.0057; -0.0119; -0.018; -0.0235; -0.0281; -0.0317; ...

-0.0346; -0.0368; -0.0385; -0.0396; -0.0402; -0.0405; -0.0408; ...

-0.0414; -0.0426; -0.0448; -0.0481; -0.0523; -0.0571; -0.0622; ...

-0.067; -0.0713; -0.0748; -0.0777; -0.0797; -0.0807; -0.0804; -0.078; ...

-0.0734; -0.0666; -0.058; -0.0485; -0.0393; -0.0314; -0.0255; -0.0216; ...

-0.0216];

Var3 = [0.0119; -0.0746; -0.1592; -0.0204; 0.0998; 0.1799; 0.2609; 0.3271; ...

0.3675; 0.3775; 0.3773; 0.381; 0.3744; 0.3668; 0.3653; 0.3736; ...

0.3843; 0.3818; 0.3608; 0.35; 0.3318; 0.3092; 0.2812; 0.2719; 0.2729; ...

0.283; 0.3012; 0.3151; 0.3164; 0.3176; 0.3215; 0.3265; 0.3346; ...

0.3519; 0.3659; 0.3761; 0.3868; 0.394; 0.4003; 0.394; 0.395; 0.3951; ...

0.3918; 0.3859; 0.3866; 0.3811; 0.3802; 0.371; 0.349; 0.3047; 0.2559; ...

0.2085; 0.1549; 0.1016; 0.0466; 0.0112; -0.0027; -0.0038; -0.0045; ...

-0.0049; -0.0048; -0.0044; -0.0038; -0.0031; -0.0027; -0.0025; ...

-0.0027; -0.0029; -0.0032; -0.0033; -0.0033; -0.0032; -0.0031; ...

-0.0032; -0.0035; -0.004; -0.0047; -0.0056; -0.0068; -0.0081; -0.0097; ...

-0.0115; -0.0133; -0.0149; -0.0162; -0.017; -0.0171; -0.0167; -0.0158; ...

-0.0146; -0.0129; -0.0108; -0.0082; -0.0048; -0.0007; 0.0041; 0.0093; ...

0.0146; 0.0213; 0.0247; 0.0247];

f1 = fit(sample,Var1,'fourier6');

f2 = fit(sample,Var2,'fourier6');

f3 = fit(sample,Var3,'fourier6');

F1 = feval(f1,x);

F2 = feval(f2,x);

F3 = feval(f3,x);

SS = F1 + F2 + F3;

coefficientValues1=coeffvalues(f1);

coefficientValues2=coeffvalues(f2);

coefficientValues3=coeffvalues(f3);

coefficientValuesSS=coefficientValues3+coefficientValues2+coefficientValues1;

subplot(4,1,4);

plot(x,F1);

grid on;

grid minor;

title('F1')

hold on;

subplot(4,1,3);

plot(x,F2);

hold on;

grid on;

grid minor;

title('F2')

hold on;

subplot(4,1,2);

plot(x,F3);

hold on;

grid on;

grid minor;

title('F3')

hold on;

[Torsten]

Looks ok to me. Do you get reasonable fit curves ?

[Dmitri Ryybak]

I think they are good. Thank you for your answer.