SWIG: Fix get_initial_step wrapping

Closes #319

doc/docs/NLopt_Python_Reference.md

@@ -340,7 +340,7 @@ Just as in the C API, you can [get and set the initial step sizes](NLopt_Referen
 
 ```
 opt.set_initial_step(dx)
-opt.get_initial_step(x)
+dx = opt.get_initial_step(x)
 ```
 
 

src/swig/nlopt.i

@@ -17,6 +17,10 @@ namespace std {
   %template(nlopt_doublevector) vector<double>;
 };
 
+// dont use the in-place version of get_initial_step
+%ignore nlopt::opt::get_initial_step;
+%rename(get_initial_step) nlopt::opt::get_initial_step_;
+
 // prepend "nlopt_" in Guile to substitute for namespace
 #if defined(SWIGGUILE)
 %rename(nlopt_opt) nlopt::opt;

test/t_guile.scm

@@ -25,7 +25,8 @@
                                            (myconstraint x grad -1 1))
                                      1e-8)
 (nlopt-opt-set-xtol-rel opt 1e-4)
-(define x (nlopt-opt-optimize opt (vector 1.234 5.678)))
+(define x0 (vector 1.234 5.678))
+(define x (nlopt-opt-optimize opt x0))
 (define minf (nlopt-opt-last-optimum-value opt))
 (define result (nlopt-opt-last-optimize-result opt))
 (display "x=")
@@ -34,3 +35,6 @@
 (display "minf=")
 (display minf)
 (newline)
+(define ini_step (nlopt-opt-get-initial-step opt x0))
+(display "initial step")
+(display ini_step)

test/t_python.py

@@ -23,9 +23,11 @@ opt.set_min_objective(myfunc)
 opt.add_inequality_constraint(lambda x, grad: myconstraint(x,grad, 2, 0), 1e-8)
 opt.add_inequality_constraint(lambda x, grad: myconstraint(x,grad, -1, 1), 1e-8)
 opt.set_xtol_rel(1e-4)
-x = opt.optimize([1.234, 5.678])
+x0 = [1.234, 5.678]
+x = opt.optimize(x0)
 minf = opt.last_optimum_value()
-print('optimum at ', x[0], x[1])
+print('optimum at ', x)
 print('minimum value = ', minf)
 print('result code = ', opt.last_optimize_result())
 print('nevals = ', opt.get_numevals())
+print('initial step =', opt.get_initial_step(x0))