# How can I make summation using variable symbol

1 view (last 30 days)
Osama Aliwat on 26 Dec 2022
Commented: Osama Aliwat on 26 Dec 2022
clc
clear
syms p
a=[0.01;0.015];%The cofficeient next to power in the IFC equation
b=[8.5;9.5];%The cofficeientin the IFC equation
B=[4e-4 0; 0 4e-4];
pl =[];
for i=1:length(a)
for j=1:length(a)
pl = pl + p(i)*B(i,j)*p(j)
end
end Also, can I later on differentiate the pl equation based on p(i)? so i can find dpl/dp1 or dpl/dp2 using such code
for i=1:length(a)
dpl(i)=diff(pl,p(i))
k(i)=1/(1-dpl(i));
end

VBBV on 26 Dec 2022
Edited: VBBV on 26 Dec 2022
clc
clear
ng = 2;
syms p [1 ng]
a=[0.01;0.015];%The cofficeient next to power in the IFC equation
b=[8.5;9.5];%The cofficeientin the IFC equation
B=[4e-4 0; 0 4e-4];
for i=1:length(a)
for j=1:length(a)
pl(j,i) = p(i)*B(i,j)*p(j);
end
Pl(i) = sum(pl(:,i));
end
Pl = sum(Pl)
Pl = dp1=diff(Pl,p1); % differentiate with p1
dp2=diff(Pl,p2); % differentiate with p2
Dp = [dp1 dp2];
k=1./(1-Dp)
k = Osama Aliwat on 26 Dec 2022
Thank you alot. For the differentiation part it will only find dp1 and dp2 while i need it to find dp3 or dp10 depending on the matrix of a thats why I used for loop

### Categories

Find more on Symbolic Math Toolbox in Help Center and File Exchange

R2021a

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!