Fix bug that Miles caught and fix tests.

Author: powerdistribution

src/differentiate.jl

@@ -185,7 +185,7 @@ for (funsym, exp) in derivative_rules
     @eval function differentiate(::SymbolParameter{$(Meta.quot(funsym))}, args, wrt)
         x = args[1]
         xp = differentiate(x, wrt)
-        if x != 0
+        if xp != 0
             return @sexpr($exp)
         else
             return 0
@@ -208,7 +208,7 @@ for (funsym, exp) in derivative_rules_bessel
         nu = args[1]
         x = args[2]
         xp = differentiate(x, wrt)
-        if x != 0
+        if xp != 0
             return @sexpr($exp)
         else
             return 0
@@ -222,3 +222,32 @@ end
 ## atan2
 ## hypot 
 ## beta, lbeta, eta, zeta, digamma
+
+function differentiate(ex::Expr, targets::Vector{Symbol})
+    n = length(targets)
+    exprs = Array(Expr, n)
+    for i in 1:n
+        exprs[i] = differentiate(ex, targets[i])
+    end
+    return exprs
+end
+
+
+differentiate(ex::Expr) = differentiate(ex, :x)
+
+function differentiate(s::String, target::Symbol)
+    differentiate(parse(s), target)
+end
+function differentiate(s::String, targets::Vector{Symbol})
+    differentiate(parse(s), targets)
+end
+function differentiate(s::String, target::String)
+    differentiate(parse(s), symbol(target))
+end
+function differentiate{T <: String}(s::String, targets::Vector{T})
+    differentiate(parse(s), map(target -> symbol(target), targets))
+end
+function differentiate(s::String)
+    differentiate(parse(s), :x)
+end
+

test/symbolic.jl

@@ -44,7 +44,7 @@
 #
 
 # @assert isequal(differentiate("sin(x) + cos(x)^2"), :(+(cos(x),*(2,cos(x)))))
-@assert isequal(differentiate("x + exp(-x) + sin(exp(x))", :x), :(+(1, *(exp(-(x)), -1), *(cos(exp(x)), exp(x)))))
+@assert isequal(differentiate("x + exp(-x) + sin(exp(x))", :x), :(+(1,*(-1,exp(-(x))),*(exp(x),cos(exp(x))))))
 
 # TODO: Make these work
 # differentiate(:(sin(x)), :x)(0.0)
@@ -60,42 +60,14 @@ y = BasicVariable(:y)
 
 @assert isequal(@sexpr(x + y), :($x + $y))
 @assert isequal(differentiate(@sexpr(3 * x), x), 3)
-@assert isequal(differentiate(:(sin(sin(x))), :x), :(*(cos(sin(x)),cos(x))))
-@assert isequal(differentiate(@sexpr(sin(sin(x))), x), :(*(cos(sin($x)),cos($x))))
+@assert isequal(differentiate(:(sin(sin(x))), :x), :(*(cos(x),cos(sin(x)))))
+@assert isequal(differentiate(@sexpr(sin(sin(x))), x), :(*(cos($x),cos(sin($x)))))
 
 function testfun(x)
     z = BasicVariable(:z)
     differentiate(@sexpr(3*x + x^2*z), z)
 end
 
-@assert isequal(testfun(x), :(*(1,^($(x),2))))
-@assert isequal(testfun(3), :(*(1,^(3,2))))
-@assert isequal(testfun(@sexpr(x+y)), :(*(1,^(+($(x),$(y)),2))))
-
-differentiate(:(2), :x)
-differentiate(:(x), :x)
-differentiate(:(x + x), :x)
-differentiate(:(x - x), :x)
-differentiate(:(2 * x), :x)
-differentiate(:(x * 2), :x)
-differentiate(:(a * x), :x)
-differentiate(:(x * a), :x)
-differentiate(:(x ^ 2), :x)
-differentiate(:(a * x ^ 2), :x)
-differentiate(:(2 ^ x), :x)
-differentiate(:(sin(x)), :x)
-differentiate(:(cos(x)), :x)
-differentiate(:(tan(x)), :x)
-differentiate(:(exp(x)), :x)
-differentiate(:(log(x)), :x)
-differentiate(:(sin(x) + sin(x)), :x)
-differentiate(:(sin(x) - cos(x)), :x)
-differentiate(:(x * sin(x)), :x)
-differentiate(:(x / sin(x)), :x)
-differentiate(:(sin(sin(x))), :x)
-differentiate(:(sin(cos(x) + sin(x))), :x)
-differentiate(:(exp(-x)), :x)
-differentiate(:(log(x^2)), :x)
-differentiate(:(x^n), :x)
-differentiate(:(n^x), :x)
-differentiate(:(n^n), :x)
+@assert isequal(testfun(x), :(^($(x),2)))
+@assert isequal(testfun(3), 9)
+@assert isequal(testfun(@sexpr(x+y)), :(^(+($x,$y),2)))