[lichmaster]

Hi Foamers,

I've stumbled upon what I think is a simple yet annoying difficulty... I looked for answers on the forum, but to no use.

I need to write a recursive function returning a surfaceScalarField.
It has several arguments, one of which is a scalar, and when this scalar is "0", then the surfaceScalarField should be 1 everywhere.
Don't know how to make it work, though...

Edit:
The function is this

surfaceScalarField int_u (int n, surfaceScalarField l, surfaceScalarField U)
{
if (n == 0)
return 1.0;

if (n == 1)
return U;

return U*int_u(n-1,l,U)+(n-1)/(2*l)*int_u(n-2,l,U);
}

[lichmaster]

Since one of the inputs is a surfaceScalarField l, a workaround is to return l/l (since l should be always positive), but I'd prefer a more efficient and robust solution

[anishtain4]

First of all it's better to pass the fields by reference rather than by value, which means
surfaceScalarField int_u (int n, surfaceScalarField& l, surfaceScalarField& U);

What is your problem with the code?

[lichmaster]

Thanks for the suggestion, I was planning to optimize the code later but this modification takes almost zero time.

If you read the function I posted above, I need to return an uniform value when n is zero, and a calculated (nonuniform) value when is greater than zero.

The problem is that i don't know how to cast the scalar 1.0 into the surfaceScalarField uniform 1.0. The line

return 1.0

gives

error: conversion from 'double' to non-scalar type "Foam::surfaceScalarField' requested"

I have bypassed it, for now, with a fake calculation "return l/l", since l should be always strictly positive, but for better efficiency and robustness I would like to know how to return (assign) an uniform surfaceScalarField.