CGO: how to return double array to go from c function?

[Curtis Paul]

Any ideas on how to properly do this?

/*

double* the_c_function()

{

     // bunch of stuff happens to populate values[]

     double *values_ptr = mxGetPr(values[0]);   //this is a Matlab c function

     printf("an element value: %lf\n", values_ptr[3]);

     return values_ptr;

}

*/

import "C"

func main () {

     returned_double_array = C.the_c_function()

     //how do I get/read the elements of returned_double_array ?

}

[Gustavo Niemeyer]

On Wed, Feb 5, 2014 at 4:14 AM, Curtis Paul <curti...@gmail.com> wrote:
> Any ideas on how to properly do this?

Something along these lines: http://play.golang.org/p/ekbp7xHwQx


gustavo @ http://niemeyer.net

[minux]

You can convert it to a Go slice of float64.

https://code.google.com/p/go-wiki/wiki/cgo

[Curtis Paul]

So far the examples have been what's documented, and doesn't really answer my question.  At least not in a way I understand.

[Curtis Paul]

So I'm able to get the elements of the array, but they are scientific notiation, and when I try doing an fmt.Println("%2.1f",Cdoublefield) I get 0.0 for any of the values.

fmt.Println(Cdoublefield) prints 8.637783107073355e-270  which is supposed to be 23.2 ...why would I get 0.0 instead of 23.2?

On Tuesday, February 4, 2014 11:14:46 PM UTC-7, Curtis Paul wrote:

[Curtis Paul]

No, it's just returning the correct value...it's not a scientific notation representation of the returned value, it's just bad data.

Does anyone know if C lang can return a double array to Go correctly?  Can Go interpret a C lang double array?

I have not been able to find any examples of doing this anywhere.....I see string and integer examples....but no float or double examples...

On Tuesday, February 4, 2014 11:14:46 PM UTC-7, Curtis Paul wrote:

[Curtis Paul]

I mean it's not returning the correct double value

[Dan Kortschak]

On Wed, 2014-02-05 at 21:01 -0800, Curtis Paul wrote:
> I mean it's not returning the correct double value

You're not passing the double to foo, so it's getting uninitialised
data.

[Dan Kortschak]

http://play.golang.org/p/sijNOPw6o4 sorry.

[Curtis Paul]

I got it now, makes sense....I appreciate the help, thanks!

On Wednesday, February 5, 2014 10:20:41 PM UTC-7, kortschak wrote:

http://play.golang.org/p/sijNOPw6o4 sorry.