`BoundsError` when using `expand_derivatives` on a particular expression in `y`, but not the same expression in `x`
Opened this issue · 1 comments
krsteffen commented
MWE (Julia Version 1.10.2, Symbolics v5.28.0, SymbolicUtils v1.5.1):
using Symbolics
expr_gen = (var, fun) -> Differential(var)(Differential(var)(((-Differential(var)(Differential(var)(fun))) / g(var))))
@syms y f(y) g(y) h(y)
expr = expr_gen(y, f(y))
expand_derivatives(expr)
expr = expr_gen(y, g(y))
expand_derivatives(expr) # Error
expr = expr_gen(y, h(y))
expand_derivatives(expr) # Error
The error message:
> show(err)
1-element ExceptionStack:
BoundsError: attempt to access 1-element Vector{Any} at index [2]
Stacktrace:
[1] getindex(A::Vector{Any}, i1::Int64)
@ Base ./essentials.jl:13
[2] expand_derivatives(O::SymbolicUtils.BasicSymbolic{Number}, simplify::Bool; occurrences::SymbolicUtils.BasicSymbolic{Real}) (repeats 2 times)
@ Symbolics ~/.julia/packages/Symbolics/Eas9m/src/diff.jl:245
[3] expand_derivatives(O::SymbolicUtils.BasicSymbolic{Number}, simplify::Bool; occurrences::Nothing)
@ Symbolics ~/.julia/packages/Symbolics/Eas9m/src/diff.jl:245
[4] expand_derivatives
@ ~/.julia/packages/Symbolics/Eas9m/src/diff.jl:171 [inlined]
[5] expand_derivatives(O::SymbolicUtils.BasicSymbolic{Number})
@ Symbolics ~/.julia/packages/Symbolics/Eas9m/src/diff.jl:171
[6] top-level scope
@ REPL[9]:1
For some reason all of the following run successfully. The only difference is replacing y with x.
using Symbolics
expr_gen = (var, fun) -> Differential(var)(Differential(var)(((-Differential(var)(Differential(var)(fun))) / g(var))))
@syms x f(x) g(x) h(x)
expr = expr_gen(x, f(x))
expand_derivatives(expr)
expr = expr_gen(x, g(x))
expand_derivatives(expr)
expr = expr_gen(x, h(x))
expand_derivatives(expr)