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Fix some problems for comparisons between tfs #622

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Merged
merged 4 commits into from
Jan 28, 2022
Merged

Fix some problems for comparisons between tfs #622

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13b2f34
Use den/num vec and fix indexing
albheim Jan 28, 2022
540cf6a
Add tests that would have failed before
albheim Jan 28, 2022
841a387
Allow compare between poly of different lengths
albheim Jan 28, 2022
35f9c62
less allocations
albheim Jan 28, 2022
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22 changes: 20 additions & 2 deletions src/types/SisoTfTypes/SisoRational.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -89,11 +89,29 @@ function evalfr(f::SisoRational{T}, s::Number) where T
end
end

==(f1::SisoRational, f2::SisoRational) = (f1.num * f2.den[1] == f2.num * f1.den[1] && f1.den * f2.den[1] == f2.den * f1.den[1]) # NOTE: Not in analogy with how it's done for SisoZpk
function ==(f1::SisoRational, f2::SisoRational)
# Get representation of num/den so index access is correct
f1num, f1den = numvec(f1), denvec(f1)
f2num, f2den = numvec(f2), denvec(f2)
(f1num * f2den[1] == f2num * f1den[1] && f1den * f2den[1] == f2den * f1den[1]) # NOTE: Not in analogy with how it's done for SisoZpk
end

# We might want to consider alowing scaled num and den as equal
function isapprox(f1::SisoRational, f2::SisoRational; rtol::Real=sqrt(eps()), atol::Real=0)
isapprox(f1.num * f2.den[1], f2.num * f1.den[1], rtol=rtol, atol=atol) && isapprox(f1.den * f2.den[1], f2.den * f1.den[1], rtol=rtol, atol=atol)
# Get representation of num/den so index access is correct
f1num, f1den = numvec(f1), denvec(f1)
f2num, f2den = numvec(f2), denvec(f2)
if length(f1num) < length(f2num)
f1num = [zeros(length(f2num) - length(f1num)); f1num]
elseif length(f2num) < length(f1num)
f2num = [zeros(length(f1num) - length(f2num)); f2num]
end
if length(f1den) < length(f2den)
f1den = [zeros(length(f2den) - length(f1den)); f1den]
elseif length(f2den) < length(f1den)
f2den = [zeros(length(f1den) - length(f2den)); f2den]
end
isapprox(f1num * f2den[1], f2num * f1den[1], rtol=rtol, atol=atol) && isapprox(f1den * f2den[1], f2den * f1den[1], rtol=rtol, atol=atol)
end

+(f1::SisoRational, f2::SisoRational) = SisoRational(f1.num*f2.den + f2.num*f1.den, f1.den*f2.den)
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5 changes: 5 additions & 0 deletions test/test_transferfunction.jl
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Expand Up @@ -37,6 +37,11 @@ z = tf("z", 0.005)
@test tf([1.0], [2.0,3.0]) == tf(π*[1.0], π*[2.0,3.0])
@test tf([1.0+2.0im], [2.0+im,3.0]) == tf((π+im)*[1+2.0im], (π+im)*[2.0+im,3.0])

# Test inequality
@test tf([1], [1]) != tf([2], [1])
@test tf([1.0], [1.0,0.0]) != tf([1.0], [2.0,0.0])
@test tf([1.0+2.0im], [2.0+im,3.0]) != tf([1+2.0im], [1.0+im,3.0])

# Test approximate equlity
# rtol should just be on the order of ϵ, no particular reason that exactly ϵ
# would work, but apparently it does
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