How can I combine if statement inside for loop?
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clc
clear all
t = [-0.095; -3.953; -7.52; 7.59; 37.66]
m6 = 1.4544e+06;
m5 = -5.7624e+05;
m4 = -1.8298e+08;
m3 = -6.3483e+08;
m2 = -1.0784e+08;
m1 = -8.3759e+07;
m0 = -7.4807e+06;
g5 = -1.8497e+06;
g4 = -7.9658e+06;
g3 = -1.5743e+07;
g2 = -3.0234e+06;
g1 = -2.0215e+06;
g0 = -1.7686e+05;
R22 = 0.4752;
for i=1:length(t)
ti=t(i)
X(i) = m0 + m1*ti + m2*ti^2 + m3*ti^3 + m4*ti^4 + m5*ti^5 + m6*ti^6;
Y(i) = g0 + g1*ti + g2*ti^2 + g3*ti^3 + g4*ti^4 + g5*ti^5;
Z(i) = X(i)/Y(i);
if Z(i) > 0
wc(i) = sqrt(R22/Z(i))
td(i) = (2/wc(i))*atan(wc(i)*ti);
else
return
end
td = min(td(j))
end
The for loop is intended to compute values of Z(i) as per corresponding values of t (i). Then, if the value of Z(i) is positive value, only then the values of wc(i) and td(i) going to be computed. For all possible values of td(i), the chosen value going to be the minimum of all.
采纳的回答
I don't know what this is trying to do, so here goes.
t = [-0.095; -3.953; -7.52; 7.59; 37.66];
m6 = 1.4544e+06;
m5 = -5.7624e+05;
m4 = -1.8298e+08;
m3 = -6.3483e+08;
m2 = -1.0784e+08;
m1 = -8.3759e+07;
m0 = -7.4807e+06;
g5 = -1.8497e+06;
g4 = -7.9658e+06;
g3 = -1.5743e+07;
g2 = -3.0234e+06;
g1 = -2.0215e+06;
g0 = -1.7686e+05;
R22 = 0.4752;
% preallocate, otherwise vectors will have mismatched length
% and indexing errors will happen
N = numel(t);
X = zeros(N,1);
Y = zeros(N,1);
Z = zeros(N,1);
wc = NaN(N,1);
td= NaN(N,1);
for i=1:N
ti=t(i);
X(i) = m0 + m1*ti + m2*ti^2 + m3*ti^3 + m4*ti^4 + m5*ti^5 + m6*ti^6;
Y(i) = g0 + g1*ti + g2*ti^2 + g3*ti^3 + g4*ti^4 + g5*ti^5;
Z(i) = X(i)/Y(i);
if Z(i) > 0
wc(i) = sqrt(R22/Z(i));
td(i) = (2/wc(i))*atan(wc(i)*ti);
% return halts all execution -- everything inside and outside the loop
% if you want to break out of the loop conditionally, use break
% if you want to skip to the next loop cycle, use continue
end
end
tdmin = min(td(~isnan(td))) % this doesn't make any sense to be inside the loop
As an aside,
% by default, both i and j are sqrt(-1).
% that's part of why using them as indices can lead to problems
td = min(td(j)) % j was not user-defined as an index
5 个评论
Suud Hasen
2021-6-3
编辑：Suud Hasen
2021-6-3
I didn't assume that the input values were the only possible ones. In this case, min(td)<0, but if min(td)>0, then there would be a problem. As the comment mentions, using zeros() to create the empty array means the default zeros in the positions associated with Z>0 would interfere with correctly calculating min(td). If instead you used NaN(), the default values would be NaN and could unambiguously be distinguished from valid td values and excluded from the minimization.
EDIT:
I went ahead and edited the code to use NaN() instead of zeros() and excluded invalid entries from the minimization. You can do something similar with wc if you want.
Suud Hasen
2021-6-3
编辑：Suud Hasen
2021-6-3
Weeell for simplification, I just rewrote this without the loop. It's easier to see what's going on.
t = [-0.095; -3.953; -7.52; 7.59; 37.66]
m6 = 1.4544e+06;
m5 = -5.7624e+05;
m4 = -1.8298e+08;
m3 = -6.3483e+08;
m2 = -1.0784e+08;
m1 = -8.3759e+07;
m0 = -7.4807e+06;
g5 = -1.8497e+06;
g4 = -7.9658e+06;
g3 = -1.5743e+07;
g2 = -3.0234e+06;
g1 = -2.0215e+06;
g0 = -1.7686e+05;
R22 = 0.4752;
X = m0 + m1*t + m2*t.^2 + m3*t.^3 + m4*t.^4 + m5*t.^5 + m6*t.^6;
Y = g0 + g1*t + g2*t.^2 + g3*t.^3 + g4*t.^4 + g5*t.^5;
Z = X./Y
wc = sqrt(R22./Z);
wc(Z<0) = NaN; % mark out invalid results
td = (2./wc).*atan(wc.*t)
tdmin = min(td(td>0)) % this would be the minimum positive value
Suud Hasen
2021-6-3
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