is it possible to make this code shorter?

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I have coded something to calculate the needed spring stifness. now i want to make the code shorter because the code is a lot of copy past, only i dont know how/if it is possible to make it shorter. the code that i have made can you see here bellow, rad is an array.
r1=x(1)/2*cos(rad(1))
r2=x(2)/2*cos(rad(1)+rad(2))
r3=x(3)/2*cos(rad(1)+rad(2)+rad(3))
r4=x(4)/2*cos(rad(1)+rad(2)+rad(3)+rad(4))
r5=x(5)/2*cos(rad(1)+rad(2)+rad(3)+rad(4)+rad(5))
r6=x(6)/2*cos(rad(1)+rad(2)+rad(3)+rad(4)+rad(5)+rad(6))
r7=x(7)/2*cos(rad(1)+rad(2)+rad(3)+rad(4)+rad(5)+rad(6)+rad(7))
r21=2*r1+r2
r31=2*(r1+r2)+r3
r41=2*(r1+r2+r3)+r4
r51=2*(r1+r2+r3+r4)+r5
r61=2*(r1+r2+r3+r4+r5)+r6
r71=2*(r1+r2+r3+r4+r5+r6)+r7
mg1=Fz(1)*r1+Fz(2)*r21+Fz(3)*r31+Fz(4)*r41+Fz(5)*r51+Fz(6)*r61+Fz(7)*r71
mg2=Fz(2)*r21+Fz(3)*r31+Fz(4)*r41+Fz(5)*r51+Fz(6)*r61+Fz(7)*r71
mg3=Fz(3)*r31+Fz(4)*r41+Fz(5)*r51+Fz(6)*r61+Fz(7)*r71
mg4=Fz(4)*r41+Fz(5)*r51+Fz(6)*r61+Fz(7)*r71
mg5=Fz(5)*r51+Fz(6)*r61+Fz(7)*r71
mg6=Fz(6)*r61+Fz(7)*r71
mg7=Fz(7)*r71
mg=[mg1 mg2 mg3 mg4 mg5 mg6 mg7]
c=-mg./rad
If some one can help me with it or has a link to a page where this is explaind i will be very happy.
  3 Comments
luuk loijen
luuk loijen on 9 Nov 2022
Edited: luuk loijen on 9 Nov 2022
rad is an array that i used like sayd in the question.
I forgot to metion that Fz is also an array.
both the arrays are a 1x7.
the numbers in the array can always be changed.
their for it will not be that helpfull if i show the arrays.

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Accepted Answer

John D'Errico
John D'Errico on 9 Nov 2022
Edited: John D'Errico on 9 Nov 2022
Even if I could make the code you show shorter, I would not do so, not to create that huge mess of variable names. EVER. Anyway, you cannot shorten anything, because you need all of those lines, because you are using numbered variable names.
Instead, replace all the cases where you create the numbered variables r1,r2,r3,r4... into ONE line. LEARN TO WRITE USING MATLAB.
r = x/2.*cos(cumsum(rad));
that creates a vector r. NOT 7 different numbered variable names. You already know how to use vectors. SO DO IT.
Next, you create a list of 6 more numbered variables, r21, r31, r41, ...
Learn from what I just said. You might now do this in one more line. Again, a vector is created.
rsum = 2*cumsum(r(2:end)) + r(1:end-1);
Finally, you create now 7 MORE numbered variable names, mg1,mg2,mg3.... All just to combine them into a vector at the end! DON'T DO IT. You are still thinking in terms of writing spreadsheets when you do this.
mg = flip(cumsum(flip(Fz.*[r(1),rsum])));
Again, it took only 3 lines of code to write. Your last line is the only line I would leave unchanged.
c = -mg./rad;

More Answers (2)

Steven Lord
Steven Lord on 9 Nov 2022
One function that will be of use to you is cumsum. This will let you avoid variables with numbered names like r1, r2, r3, etc. In general defining a numbered sequence of variables is discouraged.

David Hill
David Hill on 9 Nov 2022
r=x/2.*cos(cumsum(rad));
R=[r(1),2*cumsum(r(1:6))+r(2:7)];
mg=flip(cumsum(flip(Fz.*R)));
c=-mg./rad;

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