Re: Need test run in Matlab

[John W. Eaton]

On 1/28/19 4:03 PM, Michele wrote:
> Dear jwe,
>
> I attach the resulting diary.

Thanks.  Unfortunately, those tests may not have been the right ones to 
run to answer my questions.  I'm trying to figure out when eval will 
parse something like

  eval ("foo -opt")

as an expression (subtract the value of opt from foo) or as a command 
(call the function foo with the character string argument "-opt").  It 
seems as though eval may never evaluate its argument as a command-style 
function call if it is called with an output value:

  val = eval ("foo -opt")

Is that correct?  I suppose this would be similar to writing

  val = foo -opt

in which case the "foo -opt" part is not recognized as a command-style 
function call because that can only happen at the beginning of an 
expression.

Also the idea of the test like this:

  function f (foo)
    eval ("foo -opt")
  end
  f ()
  f (1)

was to determine whether the mere existence of a symbol was sufficient 
for eval to treat this as a subtraction or is it necessary for the 
function parameter "foo" to be defined?

Also, is this different without the eval?  What happens for something like

  function f (foo)
    foo -opt
  end

Is this always handled as a subtraction or does it depend on whether f 
is called with an argument?

In both cases, I'm assuming the function "foo" exists.

I'll try to come up with another set of tests.

jwe