Minor corrections, e.g. in simplify and show

.github/workflows/CI.yml

@@ -11,16 +11,14 @@ jobs:
   test:
     name: Tests, Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
     runs-on: ${{ matrix.os }}
-    continue-on-error: ${{ matrix.version == '1.9' }}
+    continue-on-error: ${{ matrix.version == 'nightly' }}
     strategy:
       fail-fast: false
       matrix:
         version:
-          # - '1.6' 
           - '1.7' 
           - '1' 
-          # - '1.9' 
-          # - 'nightly' 
+          - 'nightly' 
         os:  
           - ubuntu-latest
           - windows-latest

Project.toml

@@ -1,7 +1,7 @@
 name = "DescriptorSystems"
 uuid = "a81e2ce2-54d1-11eb-2c75-db236b00f339"
 authors = ["Andreas Varga <varga.andreas@gmail.com>"]
-version = "1.3.5"
+version = "1.3.6"
 
 [deps]
 MatrixPencils = "48965c70-4690-11ea-1f13-43a2532b2fa8"

ReleaseNotes.md

@@ -2,6 +2,10 @@
 
 ## Version 1.3.5
 
+Patch release to correct simplify and show for ratios of constants. 
+
+## Version 1.3.5
+
 Patch release enhancing step response computation. 
 
 ## Version 1.3.4

docs/src/index.md

@@ -102,6 +102,7 @@ The available functions in the `DescriptorSystems.jl` package cover both standar
 * **[`gh2norm`](@ref)**  `H2` norm of a descriptor system.
 * **[`glinfnorm`](@ref)**  `L∞` norm of a descriptor system.
 * **[`ghinfnorm`](@ref)**  `H∞` norm of a descriptor system.
+* **[`gnugap`](@ref)**  ν-gap distance between two descriptor systems.
 * **[`freqresp`](@ref)**   Frequency response of a descriptor system.
 * **[`timeresp`](@ref)**   Time response of a descriptor system.
 * **[`stepresp`](@ref)**   Step response of a descriptor system.

src/types/RationalTransferFunction.jl

@@ -190,8 +190,9 @@ Base.show(io::IO, sys::RationalTransferFunction) = show(io, MIME("text/plain"),
 
 function Base.show(io::IO, mime::MIME{Symbol("text/plain")}, sys::RationalTransferFunction)
     summary(io, sys); println(io)
-    p, q = Polynomials.pqs(sys)
-    if order(sys) == 0
+    n = order(sys)
+    p, q = n == 0 ? Polynomials.pqs(normalize(sys)) : Polynomials.pqs(sys)
+    if n == 0
         printpoly(io, p)
         println(io, "\n\nStatic gain.")  
         return
@@ -600,13 +601,16 @@ numerator and denominator coefficients.
 function simplify(r::RationalTransferFunction; atol::Real = 0, rtol::Real=10*eps(float(real(_eltype(r))))) 
     m = degree(r.num)
     (m == 0 || degree(r.den) == 0) && (return r)
+    var = Polynomials.indeterminate(r.num)
     pnum = r.num.coeffs
     pden = r.den.coeffs
     d, u, w,  = MatrixPencils.polgcdvw(pnum, pden, atol = atol, rtol = rtol, maxnit = 3)
+
     length(u) > m && (return r) # no cancelation, keep original r
     knum = pnum[end]/d[end]/u[end]
     kden = pden[end]/d[end]/w[end]
-    return rtf(Polynomial(u*knum,Polynomials.indeterminate(r.num)), Polynomial(w*kden,Polynomials.indeterminate(r.den)), Ts = r.Ts)
+    rs = rtf(Polynomial(u*knum,var), Polynomial(w*kden,var), Ts = r.Ts)
+    return length(u) == length(w) == 1 ? normalize(rs) : rs  
 end
 """
     Rval = evalfr(R,val) 

test/DSToolsDemo.jl

@@ -48,7 +48,7 @@ println("gzero(sysc)   #  computes all zeros (finite and infinite)")
 display(gzero(sysc))
 pause()
 
-println("Descriptor systems (A-λE,B,C,D) with singular pole pencil A-λE are not supported in DSTOOLS!")
+println("Descriptor systems (A-λE,B,C,D) with singular pole pencil A-λE are not supported!")
 println("Non-regular A-λE can be detected in several ways.\n ")
 println("(1) non-regular A-λE can be detected when building a descriptor system ")
 println("A = zeros(1,1); E = zeros(1,1); B = ones(1,1); C = ones(1,1); D = zeros(1,1);")