Series summation issue - conversion to double error
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Hi, I'm trying to write a series summation code and I'm getting the "conversion to double" error when I plot.
Here's the part of the code with trouble:
syms m
rhs = (1./(1+(2.*(t- m.*p))./tc)).* exp((-2.*r^2)./(r^2.*(1+ (2.*(t-m.*p)./tc))));
summation1 = symsum(rhs,0,1.89E5);
Where tc, r, and p are constants and t is a timespace with 36 spaces.
Is the problem that I'm asking it to sum from 0 to 1.89e5 with those 36 time spaces?
Thanks
采纳的回答
bym
2013-2-21
At some point, Matlab gives up & returns the indefinite summation. You can try this:
clc;clear
syms m
tc = 3;
p = 3;
t = 1:10;
r =2;
rhs = (1./(1+(2.*(t- m.*p))./tc)).* exp((-2.*r^2)./(r^2.*(1+ (2.*(t-m.*p)./tc))));
summation1 = symsum(rhs);
f = matlabFunction(summation1);
f(189000)
f(10)
ans =
1.0e-005 *
Columns 1 through 8
-0.2646 -0.2646 -0.2646 -0.2646 -0.2646 -0.2646 -0.2646 -0.2646
Columns 9 through 10
-0.2646 -0.2646
ans =
Columns 1 through 8
-0.0608 -0.0634 -0.0662 -0.0692 -0.0725 -0.0762 -0.0802 -0.0847
Columns 9 through 10
-0.0897 -0.0954
更多回答（1 个）
Walter Roberson
2013-2-20
You could try
double(summation1)
If that gives you the same error then your summation1 must still contain some symbolic variable. Try
symvar(summation1)
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