How to form a function using 'for loop' without 'sym' command

조회 수: 2(최근 30일)
Bathala Teja
Bathala Teja 2021년 9월 6일
댓글: Walter Roberson 2021년 9월 7일
i tried like this
m = 150;
Aos = 40;
nAi = 0;
for i=1:2:m
nAi = @(phi)nAi+cos(i*phi);
end
nA = vpa((nAi+Aos), 4)
Iam getting this error
Operator '+' is not supported for operands of type 'function_handle'.
Error in ll (line 8)
nA = vpa(nAi+Aos, 4)
  댓글 수: 2
Bathala Teja
Bathala Teja 2021년 9월 7일
Its clearly there. i want to form nA interms of phi.
But i want to evalute without sym. Any idea.....

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답변(2개)

Abolfazl Chaman Motlagh
Abolfazl Chaman Motlagh 2021년 9월 6일
Assuming you want nA be function of phi, you can use symsum for summuation :
m = 150;
Aos = 40;
syms phi k
nAi =@(phi) symsum(cos(2*k*phi),k,1,m/2);
nA =@(phi) vpa((nAi(phi)+Aos), 4);
% example
nA(pi)
ans = 
115.0
  댓글 수: 2
Abolfazl Chaman Motlagh
Abolfazl Chaman Motlagh 2021년 9월 6일
Oh! sorry, i just read the content not title of question.

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Walter Roberson
Walter Roberson 2021년 9월 6일
m = 150;
Aos = 40;
nAi = @(phi) zeros(size(phi));
for i=1:2:m
nAi = @(phi)nAi(phi)+cos(i*phi);
end
nA = @(phi) nAi(phi)+Aos
nA = function_handle with value:
@(phi)nAi(phi)+Aos
You asked to avoid sym, so it seems likely to me you want to avoid using vpa() as well. But if using a final vpa is okay, then
vpa(nA, 4)
ans = 
  댓글 수: 2
Walter Roberson
Walter Roberson 2021년 9월 7일
With vpa(), the symbol for phi appears if you are using LiveScript, but not for traditional .m files.
To get the result without using vpa:
m = 150;
Aos = 40;
nA = str2func("@(phi) " + strjoin(compose("cos(%d*theta)", 1:2:m), " + ") + " + " + string(Aos))
nA = function_handle with value:
@(phi)cos(1*theta)+cos(3*theta)+cos(5*theta)+cos(7*theta)+cos(9*theta)+cos(11*theta)+cos(13*theta)+cos(15*theta)+cos(17*theta)+cos(19*theta)+cos(21*theta)+cos(23*theta)+cos(25*theta)+cos(27*theta)+cos(29*theta)+cos(31*theta)+cos(33*theta)+cos(35*theta)+cos(37*theta)+cos(39*theta)+cos(41*theta)+cos(43*theta)+cos(45*theta)+cos(47*theta)+cos(49*theta)+cos(51*theta)+cos(53*theta)+cos(55*theta)+cos(57*theta)+cos(59*theta)+cos(61*theta)+cos(63*theta)+cos(65*theta)+cos(67*theta)+cos(69*theta)+cos(71*theta)+cos(73*theta)+cos(75*theta)+cos(77*theta)+cos(79*theta)+cos(81*theta)+cos(83*theta)+cos(85*theta)+cos(87*theta)+cos(89*theta)+cos(91*theta)+cos(93*theta)+cos(95*theta)+cos(97*theta)+cos(99*theta)+cos(101*theta)+cos(103*theta)+cos(105*theta)+cos(107*theta)+cos(109*theta)+cos(111*theta)+cos(113*theta)+cos(115*theta)+cos(117*theta)+cos(119*theta)+cos(121*theta)+cos(123*theta)+cos(125*theta)+cos(127*theta)+cos(129*theta)+cos(131*theta)+cos(133*theta)+cos(135*theta)+cos(137*theta)+cos(139*theta)+cos(141*theta)+cos(143*theta)+cos(145*theta)+cos(147*theta)+cos(149*theta)+40

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