Anonymous Function
4 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Jerry Walker
am 24 Jun. 2011
Kommentiert: Steven Lord
am 31 Jan. 2023
[EDIT: 20110623 22:10 CDT - reformat - WDR]
I am having considerable difficulty with the program below. My goal is to be able to enter or change the Current Density (J) in the integral as an anonymous function. When j = 2*cos(theta)/r^3, the result should be about 31.4. Are there any other methods that would allow me to enter J inot the integral?
When I run I get the following error message:
??? Undefined function or method 'mtimes' for input arguments of type 'function_handle'.
When I swap the "%" on the operator inside the loops I get a 31.4, a good result.
clc
clear
close
r = 0.2;
dt = .1;
dp = .1;
jinput = input('Enter an expression for the Current Density (J)... > ','s')
jfactor = eval(['@(r,theta,phi)' jinput]);
% set initial total sum to zero
sum1 = 0;
% outer integral loop
for theta = 0:dt:pi/2
% inner integral loop
for phi = 0:dp:2*pi
% add the partial sums to the total sum
sum1 = sum1 + jfactor*r^2*sin(theta)*dt*dp;
%sum1 = sum1 + 2*cos(theta)/r^3*r^2*sin(theta)*dt*dp;
end
end
% display the output
fprintf('>The total current through the defined spherical shell is %g A.\n', sum1)
1 Kommentar
Steven Lord
am 31 Jan. 2023
%{
jfactor = eval(['@(r,theta,phi)' jinput]);
%}
Don't use eval. Use str2func. [I've commented out the code above so the code below can run.] Since the input function isn't supported when running code in MATLAB Answers I've hard-coded the body of the function below.
jinput = 'r+theta.^phi';
jfactor = str2func(['@(r, theta, phi) ', jinput])
% check
jfactor(1, 2, 3) % 1+2^3 = 9
Akzeptierte Antwort
Walter Roberson
am 24 Jun. 2011
jfactor becomes a function, and that function needs to be passed arguments.
sum1 = sum1 + jfactor(r,theta,phi)*r^2*sin(theta)*dt*dp;
0 Kommentare
Weitere Antworten (2)
Siphumelele Vatsha
am 31 Jan. 2023
sum1 = sum1 + jfactor(r,theta,phi)*r^2*sin(theta)*dt*dp;
0 Kommentare
Siehe auch
Kategorien
Mehr zu Robotics finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!