begin, end
OMhelp is designed to be embedded in computer source code.
In fact, it is language independent and can be can combine source
code files in multiple languages to form one documentation system.
Only the text between a begin
and a $end is processed
by OMhelp.
It is intended that these commands be comments in the language.
Source Code Languages
This example covers languages that only have one line comments; e.g.,
Matlab, Fortran, R.
(The R language uses the $ character, this it may be necessary to change
the OMhelp KeyCharacter
.)
newlinech
The newlinech
command is used to specify which character is
used for one line comments.
near_equal_f.f
Use the editor of your choice to
create the file near_equal_f.f in the
xam directory
with the following contents:
c $begin near_equal_f$$ $newlinech c$$
c $spell
c $$
c
c $section Determine if Two Values Are Nearly Equal$$
c
c $head Syntax$$
c $icode%e% = near_equal_f(%x%, %y%, %r%, %a%)%$$
c
c $head Purpose$$
c Returns true,
c if $icode x$$ is nearly equal to $icode y$$ and false otherwise.
c
c $head x$$
c The argument $icode x$$ has prototype
c $codei%
c double precision %x%
c %$$
c
c $head y$$
c The argument $icode y$$ has prototype
c $codei%
c double precision %y%
c %$$
c
c $head r$$
c The relative error criteria $icode r$$ has prototype
c $codei%
c double precision %r%
c %$$
c It must be greater than or equal zero.
c The relative error condition is satisfied if
c $latex \[
c | x - y | \leq r ( |x| + |y| )
c \] $$
c where $latex \leq$$ denotes less than or equal.
c
c $head a$$
c The absolute error criteria $icode a$$ has prototype
c $codei%
c double precision %a%
c %$$
c It must be greater than or equal zero.
c The absolute error condition is satisfied if
c $latex \[
c | x - y | \leq a
c \] $$
c
c $head e$$
c The return value $icode e$$ has prototype
c $codei%
c logical %e%
c %$$
c If either the relative or absolute error condition is satisfied,
c it is true.
c Otherwise, it is false.
c
c
c $head Example$$
c The following is an example and test of $code near_equal_f$$.
c It returns true if the test succeeds and false if it fails.
c
c $comment no indent, start output at text following END COPYRIGHT$$
c $code
c $verbatim%omh/getstarted/ok_near_equal_f.f%
c 5%c BEGIN_OK_NEAR_EQUAL_F%c END_OK_NEAR_EQUAL_F%0
c %$$
c $$
c
c $end
c ---------------------------------------------------------------------------
logical function near_equal_f(x, y, r, a)
double precision x, y, r, a
double precision ax, ay, d
ax = dabs(x);
ay = dabs(y);
ad = dabs(x - y);
near_equal_f = (ad .le. a) .or. (ad .le. r * (ax + ay));
end
Example In This Web Site
You can view the result of making near_equal_f.f
part of the OMhelp help web site by selecting near_equal_f
.
Input File: omh/getstarted/start_oneline.omh
