How to write conversion functions (original) (raw)

Scilab 5.3.3

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• Operation
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Scilab help >> Matlab to Scilab Conversion Tips > sci_files

sci_files

How to write conversion functions

Description

To convert calls to Matlab functions, mfile2sci uses a function calledsci_<Matlab_function_name>. All these functions are defined in sci_files in directory SCI/modules/m2sci/macros/sci_files/. The set of sci_files given in Scilab distribution does not allow to convert calls to all Matlab functions yet. However, a Scilab user can add sci_files (for Matlab functions or for user defined functions) to Scilab using the following tips.

In M2SCI, a function call is considered as a "tree" (it is also the case for the instructions of the file to convert), represented in Scilab by a tlist with following fields:

• name
  Matlab function name
  lhsnb
  number of Matlab function output parameters
  lhs
  list of Matlab function output parameters
  rhs
  list of Matlab function input parameters

A sci_function has one input called tree which is also the output of the function. A sci_function has to convert this incoming "tree" so that it is compatible with Scilab by changing name, lhsnb, lhs and/or rhs. The other task that has to be done by this function is inference. Incoming tree contains inference data in its lhs that have to be updated with what can be infered for the outputs of this function.

Some useful functions have been written to help to create M2SCI tlists while writing this conversion function:

• Funcall
  create a tree representing a function call
  Operation
  create a tree representing an operation
  Variable
  create a tree representing a variable
  Cste
  create a tree representing a constante value
  Infer
  create a tree representing inference data
  Type
  create a tree representing type for inference
  Equal
  create a tree representing an instruction

Some other functions have been designed to get properties of operands/inputs. Considering A is tlist used in macro tree, you can use the following functions:

Some other functions have been written for specific needs while writing conversion files:

• first_non_singleton
  is an equivalent to firstnonsingleton for an M2SCI tlist. Calling sequence: dim = first_non_singleton(A)
  gettempvar
  generates a temporary variable having a name which does not already exist. Calling sequence:v = gettempvar()
  insert
  allows to insert instructions. Calling sequence:insert(Equal(...),opt) with opt~=1 to insert before current instruction and opt=1 to insert after it.
  getoperands
  can be used to get each operand as a variable. Calling sequence: [A,B] = getoperands(operation_tlist)
  getrhs
  can be used to get each parameter as a variable. Calling sequence: [A,...] = getrhs(funcall_tlist)
  convert2double
  change type of input when this type is not implemented for a particular function is Scilab. Calling sequence:A = convert2double(A)

To have more information about how to write such files, refer to directory SCI/modules/m2sci/macros/sci_files/ which gives many examples from very simple ones (e.g. sci_abs.sci) to very complex ones (e.g. sci_zeros.sci).

See Also

• m2scideclare — Giving tips to help M2SCI...
• Funcall — Create a tree representing a function call
• Operation — Create a tree representing an operation
• Variable — Create a tree representing a variable
• Cste — Create a tree representing a constant
• Infer — Create a tree containing inference data
• Type — Create a tree containing type inference data
• Equal — Create a tree representing an instruction