MCP-0011: Custom Reductions

[modelica-trac-importer]

Modified by dietmarw on 28 Apr 2016 09:22 UTC
This is a discussion regarding MCP-0011_CustomReductions:

• https://svn.modelica.org/projects/MCP/public/MCP-0011_CustomReductions/

It concerns calling user-defined functions in reduction expressions. Something like:

myProduct(2*c for c in complexArray)

Please comment on the proposal in this trac ticket.

---

Modified by dietmarw on 28 Apr 2016 09:21 UTC
This is a discussion regarding MCPI-0011_CustomReductions:

• https://svn.modelica.org/projects/MCP/public/MCP-0011_CustomReductions/

It concerns calling user-defined functions in reduction expressions. Something like:

myProduct(2*c for c in complexArray)

Please comment on the proposal in this trac ticket.

---

Modified by dietmarw on 28 Apr 2016 09:20 UTC
This is a discussion regarding MCPI-0011_CustomReductions:

• https://svn.modelica.org/projects/MCP/public/MCP-0010_ReductionFilter/

It concerns calling user-defined functions in reduction expressions. Something like:

myProduct(2*c for c in complexArray)

Please comment on the proposal in this trac ticket.

---

Reported by sjoelund.se on 23 May 2014 11:03 UTC
This is a discussion regarding MCPI-0011_CustomReductions:
https://svn.modelica.org/projects/MCP-Ideas/MAinternal/MCPI-0011_CustomReductions/MCPI-0011_CustomReduction.pdf

It concerns calling user-defined functions in reduction expressions. Something like:

myProduct(2*c for c in complexArray)

Please comment on the proposal in this trac ticket.

---

Migrated-From: https://trac.modelica.org/Modelica/ticket/1500

[modelica-trac-importer]

Comment by jmattsson on 23 May 2014 11:22 UTC
As far as I can tell the only benefit is that you only need:

function myProduct
  input Complex a;
  input Complex b;
  output Complex c;
algorithm
  c := a * b;
end myProduct;

myProduct(2*c for c in complexArray);

instead of:

function myProduct
  input Complex a[:];
  output Complex c;
algorithm
  c := Complex(0);
  for b in a loop
    c := c * b;
  end for;
end myProduct;

myProduct({2*c for c in complexArray});

Or am I missing something?

[modelica-trac-importer]

Comment by jmattsson on 23 May 2014 11:33 UTC
Of course, if you already happen to have myProduct:

function myProduct
  input Complex a;
  input Complex b;
  output Complex c;
algorithm
  // Calculate c
end myProduct;

Then the example becomes:

myProduct(2*c for c in complexArray);

instead of:

function myProductArr
  input Complex a[:];
  output Complex c;
algorithm
  c := Complex(0);
  for b in a loop
    c := myProduct(c, b);
  end for;
end myProductArr;

myProductArr({2*c for c in complexArray});

I still think that it is more complication than it is worth, given that we already have array comprehensions. Also, when writing it as a function that takes an array the user can decide on folding order and default values.

Note that requiring that there are default values for the inputs to the function precludes using Complex.'+' like you did in the example, since binary operator functions aren't allowed to have default values on the first two inputs.