How to use indexing format inside symsum function

2023 7 1
2 个回答
更新时间：2023 7 1
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clc;
close all;
clear all;
N=2;alpha=0.5
t=zeros(1,N)
l=1:N;
t(l)=solve(chebyshevT(N,2*x-1),x);
syms m
L=symsum(t(m),m,1,2)

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SUMIT
SUMIT 2023-7-1
After running the program i got
''Invalid indexing or function definition. When defining a function, ensure that the arguments are symbolic variables and the body of the function is a SYM expression. When indexing, the
input must be numeric, logical, or ':'.''
please help me out
Paul
Paul 2023-7-1
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Ran in:
Hi Sumit,
The code results in a different error because x is not defined. Is x supposed to be symbolic variable? What is the function chebyshev? It might be helpful if to explain what the code is trying to accomplish.
N=2;alpha=0.5;
t=zeros(1,N);
l=1:N;
t(l)=solve(chebyshevT(N,2*x-1),x);
Unrecognized function or variable 'x'.
syms m
L=symsum(t(m),m,1,2)

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回答（2 个）

Steven Lord
Steven Lord 2023-7-1
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Ran in:
If you want to sum the elements of a symbolic array, just use sum.
syms x
f = x.^(0:5)
f = 
s = sum(f)
s = 
Walter Roberson
Walter Roberson 2023-7-1

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It is never possible to index by a symbolic variable at the MATLAB level. (There are some cases in the internal symbolic computing engine where indexing by a symbolic variable is possible.)

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