How can I simplify the symbolic expressions?

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Ali Almakhmari
Ali Almakhmari 2023-9-11
编辑： Ali Almakhmari 2023-9-11
Ran in:
I hate the fact that solve keeps outputting symbolic expressions with extremely large numbers, when clearly it can simplify further and get rid of those numbers. How can I force it to do that? Its okay with me if I can get an approximation up 6 decimal places.
clear
clc
syms q_bar delta_o theta1 theta2 q S CL_alpha CL_delta b e KT
eqn1 = (2*theta1 - theta2 - q_bar.*theta1 + q_bar.*theta2) == (-0.4805020381.*q_bar.*delta_o);
eqn2 = (-theta1 + theta2 - 2.*q_bar.*theta2) == (-0.0051005137.*q_bar.*delta_o);
sol = solve(eqn1,eqn2,theta1,theta2);
L1 = q.*S.*CL_alpha.*sol.theta1;
L2 = q.*S.*CL_alpha.*sol.theta2 + q.*S.*CL_delta.*delta_o;
eqn1 = (0.25.*L1.*b + 0.75.*L2.*b) == 0;
a=solve(eqn1,q_bar)
a = 
  1 个评论
Torsten
Torsten 2023-9-11
If you need 6 decimal places, why do you supply model parameters with 10 decimal places ?
-0.4805020381*q_bar
-0.0051005137*q_bar

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采纳的回答

John D'Errico
John D'Errico 2023-9-11
编辑：John D'Errico 2023-9-11
Ran in:
clear
clc
syms q_bar delta_o theta1 theta2 q S CL_alpha CL_delta b e KT
eqn1 = (2*theta1 - theta2 - q_bar.*theta1 + q_bar.*theta2) == (-0.4805020381.*q_bar.*delta_o);
eqn2 = (-theta1 + theta2 - 2.*q_bar.*theta2) == (-0.0051005137.*q_bar.*delta_o);
sol = solve(eqn1,eqn2,theta1,theta2);
L1 = q.*S.*CL_alpha.*sol.theta1;
L2 = q.*S.*CL_alpha.*sol.theta2 + q.*S.*CL_delta.*delta_o;
eqn1 = (0.25.*L1.*b + 0.75.*L2.*b) == 0;
a=solve(eqn1,q_bar)
a = 
They are simple already. At least, as simple as they can be. You have unknowns in there, inside and outside of the square roots. I suppose you could play around, and make it different, but simpify will not find anything glaring to reduce there.
Can you make the numbers smaller? Well, yes, you can force VPA to round them.
vpa(a,10)
ans = 
Is that simpler? I guess.
  1 个评论
Ali Almakhmari
Ali Almakhmari 2023-9-11
编辑：Ali Almakhmari 2023-9-11
Not really. I mean, you can take 5.642719936e17 in common from numerator and denominator and have everything simplify to have all numbers between 0.1 to 10 instead of so complicated like that with high numbers.

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