How to have use int() in a for loop?

Hi there

The goal of this loop is to plot the value of A over a defined set of angles values al.

I believe the integrating function is giving the following error:

Error using symengine

Invalid argument.

Error in sym/int (line 162)

rSym = mupadmex('symobj::intdef',f.s,x.s,a.s,b.s,options);

Is there a way to integrate a and gradually plot the values from an array?

I hope this makes sense

syms x
B=(pi-asin(1/2))
al=asin(1/2):0.001:B;
V=200*sin(x);

i=1;
for i=al(i)
    F=double(subs(100*2*pi+int(V,x,al,B)-100*(B-al)))
    Vdc=F/(2*pi);
    A=(Vdc-100)/2
    plot(al,A)
    i=i+1
end

Answer 1

[Walter Roberson]

syms x
B=(pi-asin(1/2));
al=asin(1/2):0.001:B;
V=200*sin(x);
nal = numel(al);
A = zeros(size(al));
for i = 1 : nal
    F=double(subs(100*2*pi+int(V,x,al(i),B)-100*(B-al(i))));
    Vdc=F/(2*pi);
    A(i)=(Vdc-100)/2;
end
plot(al, A)

This is rather slow (!!) The secret to doing int() in a for loop faster, is not to do int() inside a for loop. Instead, do the int() once before the loop, using a symbolic lower bound, and then subs() the numeric lower bound into that; you can do all the calculations in vectorized form.

Answer 2

[KSSV]

syms x
B=(pi-asin(1/2))
al=asin(1/2):0.001:B;
V=200*sin(x);

i=1;
for i=1:length(al)
    I = double(int(V,x,al(i),B)) ; 
    F=((100*2*pi+I-100*(B-al(i))))
    Vdc(i) = F/(2*pi);
    A(i) =(Vdc-100)/2 ;
end