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Improve 'simplify' function #22

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merged 1 commit into from
Oct 13, 2013
Merged

Improve 'simplify' function #22

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29 changes: 29 additions & 0 deletions src/symbolic.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,31 @@ function simplify(ex::Expr)
return new_ex
end

function sum_numeric_args(args)
sum = 0
sym_args = {}
for arg in args
if isa(arg, Number)
sum += arg
else
sym_args = [sym_args, arg]
end
end
(sum, sym_args)
end

function mul_numeric_args(args)
prod = 1
sym_args = {}
for arg in args
if isa(arg, Number)
prod *= arg
else
sym_args = [sym_args, arg]
end
end
(prod, sym_args)
end

# Handles all lengths for ex.args
# Removes any 0's in a sum
Expand All @@ -113,6 +138,8 @@ function simplify(::SymbolParameter{:+}, args)
elseif length(new_args) == 1
return new_args[1]
else
(sum, sym_args) = sum_numeric_args(new_args)
new_args = sum==0 ? sym_args : [sum, sym_args]
return Expr(:call, :+, new_args...)
end
end
Expand Down Expand Up @@ -144,6 +171,8 @@ function simplify(::SymbolParameter{:*}, args)
elseif any(new_args .== 0)
return 0
else
(prod, sym_args) = mul_numeric_args(new_args)
new_args = prod==1 ? sym_args : [prod, sym_args]
return Expr(:call, :*, new_args...)
end
end
Expand Down
16 changes: 15 additions & 1 deletion test/symbolic.jl
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Expand Up @@ -15,7 +15,7 @@
@assert isequal(differentiate(:(x * a), :x), :a)
@assert isequal(differentiate(:(x ^ 2), :x), :(2 * x))
@assert isequal(differentiate(:(a * x ^ 2), :x), :(a * (2 * x)))
@assert isequal(differentiate(:(2 ^ x), :x), :(*(^(2, x), 0.6931471805599453)))
@assert isequal(differentiate(:(2 ^ x), :x), :(*(0.6931471805599453, ^(2, x))))
@assert isequal(differentiate(:(sin(x)), :x), :(cos(x)))
@assert isequal(differentiate(:(cos(x)), :x), :(*(-1,sin(x)))) # needs a better simplify
@assert isequal(differentiate(:(tan(x)), :x), :(1 + tan(x)^2))
Expand Down Expand Up @@ -74,3 +74,17 @@ end
@assert isequal(testfun(x), :(^($(x),2)))
@assert isequal(testfun(3), 9)
@assert isequal(testfun(@sexpr(x+y)), :(^(+($x,$y),2)))

#
# Simplify tests
#

@assert isequal(simplify(:(x+y)), :(+(x,y)))
@assert isequal(simplify(:(x+3)), :(+(3,x)))
@assert isequal(simplify(:(x+3+4)), :(+(7,x)))
@assert isequal(simplify(:(2+y+x+3)), :(+(5,y,x)))

@assert isequal(simplify(:(x*y)), :(*(x,y)))
@assert isequal(simplify(:(x*3)), :(*(3,x)))
@assert isequal(simplify(:(x*3*4)), :(*(12,x)))
@assert isequal(simplify(:(2*y*x*3)), :(*(6,y,x)))