how can a symbolic derivative be vectorized automatically?
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Marko
am 20 Okt. 2023
Beantwortet: Walter Roberson
am 20 Okt. 2023
Hello,
here is the simplified problem.
I have a symblic function with three arguments. And the derivative of f wrt. b
syms a b c
f = a*sin(b)*exp(c)
df = diff(f,b)
The solution is:
df = a*exp(c)*cos(b)
Now i will use this derivatve in a numeric script. And the argumetns a,b,c are vectors:
a=rand(10,1);
b=rand(10,1);
c=rand(10,1);
My current approach is to modify the derivative manualy: (adding "dots")
df = a.*exp(c).*cos(b)
Is there a way how i can change a symblic expression automatically?
My equations are has 80 or more characters and the derivatives has 2x to 3x the amount of characters.
So an automatic transform into an vectorized version would help me a lot.
Best regards,
MJ
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Akzeptierte Antwort
Stephen23
am 20 Okt. 2023
Use MATLABFUNCTION:
syms a b c
f = a*sin(b)*exp(c)
df = diff(f,b)
mf = matlabFunction(df)
a=rand(10,1);
b=rand(10,1);
c=rand(10,1);
mf(a,b,c)
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Weitere Antworten (2)
Dyuman Joshi
am 20 Okt. 2023
Convert it to a function handle -
syms a b c
f = a*sin(b)*exp(c)
df = diff(f,b)
%Convert the symbolic function to an anonymous function
fun = matlabFunction(df)
a=rand(10,1);
b=rand(10,1);
c=rand(10,1);
fun(a,b,c)
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Walter Roberson
am 20 Okt. 2023
format long g
syms a b c
f(a,b,c) = a*sin(b)*exp(c)
df = diff(f,b)
A = rand(10,1);
B = rand(10,1);
C = rand(10,1);
D = df(A, B, C)
vpa(D)
double(D)
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