Table values as input to a function

Hello!

Im trying to execute the following equation as shown in the image:

Having trouble using the values in the table as input to the fuction.

How should i do this? (quite new at matalb).

The current code is down below

syms P_lv(t) C1 C2 C3 C4 R0 R1 R2 R3 R4 Rb Rp Rl Rr L1 L2 L3 L4 R_lv t
syms dens l h d E u
syms am fm t phi_m m


[C1, C2, C3, C4] = deal(6.158 * 10^10);
[L1, L2, L3, L4] = deal(344294);
[R1, R2, R3, R4] = deal(2.651 * 10^12);
[Rb, Rr, Rp, Rl] = deal(2.2 * 10^9);

%P_lv(t) = 1/0.0075 * (a0 + synsum(am*sin(2*pi*fm*t+phi_m),m,1,10));

table_A = table([0;1;2;3;4;5;6;7;8;9;10],...
    [0;1;2;3;4;5;6;7;8;9;10],...
    [80;32.1;16;10.5;5;2.6;3.9;2.4;1;1.8;1.5],...
    [0;-3.11;-1.25;0.71;2.8;-2.44;-0.84;1.38;2.7;-2.22;-0.14],...
    'Variablenames',{'m','fm','am','phi_m'});

f = @testy;
output_B = varfun(f,table_A);



function y = testy(am, fm, t, phi_m, m)
    y = 1/0.0075 * (80 + symsum(am*sin(2*pi*fm*t+phi_m),m,1,10));
end
   

Answer 1

[Asvin Kumar]

The desired expression can be evaluated in two ways. One of them uses symbolic math while the other avoids symbolic math altogether. Both these approaches use the data stored in the table. Have a look at the modified code below:

syms P_lv(t) C1 C2 C3 C4 R0 R1 R2 R3 R4 Rb Rp Rl Rr L1 L2 L3 L4 R_lv t 
syms dens l h d E u 
  
[C1, C2, C3, C4] = deal(6.158 * 10^10); 
[L1, L2, L3, L4] = deal(344294); 
[R1, R2, R3, R4] = deal(2.651 * 10^12); 
[Rb, Rr, Rp, Rl] = deal(2.2 * 10^9); 
  
%P_lv(t) = 1/0.0075 * (a0 + synsum(am*sin(2*pi*fm*t+phi_m),m,1,10)); 
  
table_A = table([0;1;2;3;4;5;6;7;8;9;10],... 
    [80;32.1;16;10.5;5;2.6;3.9;2.4;1;1.8;1.5],... 
    [0;-3.11;-1.25;0.71;2.8;-2.44;-0.84;1.38;2.7;-2.22;-0.14],... 
    'Variablenames',{'fm','am','phi_m'}); 
f = @testy; 
t = 0; % set t here 
  
% Approach which uses symbolic math 
output_B = rowfun(f,table_A(2:end,:),'SeparateInputs',false,'OutputFormat','uniform'); 
P_lv = double(sum(subs(output_B,t))); 
  
% Approach which doesn't use symbolic math 
P_lv2 = testy2(table_A,t); 
  
function y = testy(vals,t) 
    syms am fm t phi_m 
    a0 = 80/10; 
    exprn = 1/0.0075 * (a0 + am*sin(2*pi*fm*t+phi_m)); 
    y = subs(exprn, [fm,am,phi_m],vals); 
end 
  
function y = testy2(T,t) 
    a0 = T{1,2}; 
    T = T(2:end,:); 
    y = 2*pi*T.fm*t+T.phi_m; 
    y = T.am.*sin(y); 
    y = 1/0.0075*(a0+sum(y)); 
end 

The significant changes are:

1. Removed the ‘m’ variable from table_A.
2. rowfun is used to evaluate the user-defined function testy at every row of table_A.
3. The symbolic expression for each row is evaluated at t and all the values are then summed up. The value of a0 has been appropriately modified.
4. The user-defined function testy2, on the other hand, computes the value of the desired expression for a value t without using any symbolic math.

The ‘SeparateInputs’ parameter in the rowfun function ensures that each row is passed as a vector to the specified function. The ‘OutputFormat’ parameter ensures that the output is of class sym instead of a table.

For more details have a look at:

https://www.mathworks.com/help/matlab/ref/rowfun.html

https://www.mathworks.com/help/symbolic/subs.html