getScalarDouble Get scalar double variable.

## Syntax

    int getScalarDouble(void* _pvCtx, int* _piAddress, double* _pdblReal)

    int getNamedScalarDouble(void* _pvCtx, const char* _pstName, double* _pdblReal)

## Arguments

_pvCtx

  Scilab environment pointer, pass in "pvApiCtx" provided by api_scilab.h.

_piAddress

  Address of the Scilab variable.

_pstName

  Name of the variable for "named" functions.

_pdblReal

  Double value.

## Return value

if successful 0, otherwise print error(s) message(s) in the Scilab console and returns first error number.