Improvements to lambdify, to_proc

Author: rajithv

lib/symengine.rb

@@ -33,12 +33,19 @@ def Function(n)
     def evalf(operand, prec=53, real=false)
         return _evalf(operand, prec, real)
     end
-    def lambdify(exp, syms)
+    def lambdify(exp, *syms)
       eval(SymEngine::Utils::lambdify_code(exp, syms))
     end
   end
   module Utils
     class << self
+      REPLACEMENTS = { sin: 'Math.sin', cos: 'Math.cos', tan: 'Math.tan',
+                         asin: 'Math.asin', acos: 'Math.acos', atan: 'Math.atan',
+                         sinh: 'Math.sinh', cosh: 'Math.cosh', tanh: 'Math.tanh',
+                         asinh: 'Math.asinh', acosh: 'Math.acosh', atanh: 'Math.atanh', 
+                         pi: 'Math::PI', E: 'Math::E',
+                         dirichlet_eta: 'SymEngine::Utils::evalf_dirichlet_eta',
+                         zeta: 'SymEngine::Utils::evalf_zeta', gamma: 'Math.gamma' }.map { |from, to| [/(\b#{from}\b)/, to] }.to_h.freeze
       def evalf_dirichlet_eta(exp)
         SymEngine::evalf(SymEngine::dirichlet_eta(exp))
       end
@@ -49,14 +56,7 @@ def lambdify_code(exp, syms)
         str = exp.to_s  
         sym_map = syms.join(",")
         str.gsub!(/[\d\.]+/, 'Rational(\0,1)')
-        replacements = { sin:"Math.sin", cos: "Math.cos", tan: "Math.tan",
-                         asin:"Math.asin", acos: "Math.acos", atan: "Math.atan",
-                         sinh:"Math.sinh", cosh: "Math.cosh", tanh: "Math.tanh",
-                         asinh:"Math.asinh", acosh: "Math.acosh", atanh: "Math.atanh", 
-                         pi: "Math::PI", E: "Math::E",
-                         dirichlet_eta: "SymEngine::Utils::evalf_dirichlet_eta",
-                         zeta: "SymEngine::Utils::evalf_zeta", gamma: "Math.gamma" }
-        replacements.each {|key, value| str.gsub!(/(\b#{key}\b)/, value)}
+        str = REPLACEMENTS.inject(str) { |res, (from, to)| res.gsub(from, to)}
         "lambda { | #{sym_map} | #{str} }"
       end
     end

lib/symengine/basic.rb

@@ -13,11 +13,18 @@ def free_symbols
     def abs
       SymEngine::abs(self)
     end
-    def to_proc()
-      if self.free_symbols.count > 1
-        raise ArgumentError, "Too many free symbols! Only 1 allowed. Found #{self.free_symbols.count}."
+    def to_proc(*args)
+      if(args.length == 0)
+        if self.free_symbols.count > 1
+          raise ArgumentError, "Too many free symbols! Only 1 allowed. Found #{self.free_symbols.count}."
+        end
+        SymEngine::lambdify(self, self.free_symbols.map {|s| s})
+      else
+        if self.free_symbols.count > args.length
+          raise ArgumentError, "#{self.free_symbols.count} Free Symbols. Only #{args.length} given."
+        end
+        SymEngine::lambdify(self, args)
       end
-      SymEngine::lambdify(self, self.free_symbols.map {|s| s.to_s})
     end
   end
 end

spec/lambdify_spec.rb

@@ -76,6 +76,7 @@ def l(code)
     it 'creates procs' do
       expect([1, 2, 3, 4, 5].map(&func)).to eq([10, 20, 30, 40, 50])
       expect { [[1, 2], [3, 4]].map(&func2) }.to raise_error(ArgumentError)
+      expect([[1, 2], [3, 4]].map(&func2.to_proc(x, y))).to eq([13, 17])
    end
   end