fix c=0, g=0 (#29)

* fix c=0, g=0

Co-authored-by: Tim Holy <tim.holy@gmail.com>

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Co-authored-by: youdongguo <1010705897@qq.com>
Co-authored-by: Tim Holy <tim.holy@gmail.com>

Author: 3 people

src/NMFMerge.jl

@@ -148,8 +148,13 @@ function solve_remix(S, T, id1, id2)
     b = sqrt(τ^2/4-δ)
     λ_max = τ/2+b
     λ_min = δ/λ_max
-    ξ = (h1h1-h2h2+2b)/((h1h2+c*h2h2)*2)
-    u = (ξ, 1)./sqrt(1+2ξ*c+ξ^2)
+    den = (h1h2+c*h2h2)*2
+    if iszero(den)
+        u = h1h1 >= h2h2 ? (one(c), zero(c)) : (zero(c), one(c))
+    else
+        ξ = (h1h1-h2h2+2b)/den
+        u = (ξ, 1)./sqrt(1+2ξ*c+ξ^2)
+    end
     return c, λ_min, u
 end