std.algorithm.map - function by reference

[kuba via Digitalmars-d-learn]

Hi there,
I was wondering if std.algorithm.map can take functions with 
parameters passed by reference? The main point here is to avoid 
unnecessary copies by perhaps I'm using the wrong tool for the 
job.

Thank you,
kuba

////////////////////////

import std.algorithm, std.math;
import std.stdio;

double ksqrCpy( double _in){
     return sqrt(_in);
}

void ksqrRef(ref double _in){
     _in = sqrt(_in);
}

void main() {
     double[] arr1 = [ 1, 2, 3, 4 ];
     map!ksqrRef (arr1);
     writeln("a ref : ", arr1);
     auto byCpy= map!ksqrCpy (arr1);
     writeln("a copy: ", byCpy);
}