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An overview of the Assert module.
The goal of this module is to provide functions to check the behavior of some other functions, for example in unit tests. We emphasize the use of consistent tools for testing numerical issues, with the goal of testing numerical algorithms more easily. In particular, we provide a comparison function for two floating point numbers, which allows to check that two numbers are "numerically almost equal", i.e. that the relative error is small.
assert_checktrue function allows to
check that a matrix of booleans is true.
The following assertion fails and generate an error.
assert_checktrue ( [%t %F] );
assert_checkequal function allows to
check that two variables are equal.
The following assertion is a success and runs silently.
assert_checkequal ( %nan , %nan );
assert_checkalmostequal function allows to
check that a computed result is close to an expected result.
In the following script, we check that
is close to
expected=1.23457, but that
11 digits have been lost with respect to the maximum
assert_checkalmostequal ( 1.23456 , 1.23457 , 1.e11*%eps );
A particular feature of the module is that all the assert functions
have the same output arguments.
This feature allows to get a uniform behavior and supports a
simple management of the errors in the case where an assertion is
For example, consider the function
which calling sequence is:
flag = assert_checktrue ( condition ) flag = assert_checktrue ( condition ) [flag,errmsg] = assert_checktrue ( condition )
If any entry in condition is false,
if the errmsg output variable is not used, an error is generated,
if the errmsg output variable is used, no error is generated.
The reason of this behavior is to be able to use assertions both in scripts (e.g. unit tests) and in functions. For example, in a typical unit test, the statement:
assert_checktrue ( 1+1==12 );
will generate an error, as expected.
On the other hand, consider the situation where we want to insert
assertions checkings in a function.
We might want to manage the case where the assertion fails.
In this case, the calling sequence
assert_checktrue ( condition )
generates an error, which interrupts the execution.
We may want to avoid this, by catching the error generated by
This requires to use the
execstr function and
may lead to the following source code.
function y=myfunction(x) ierr=execstr("assert_checktrue ( x==12 )","errcatch"); if ( ierr <> 0 ) then error("Oups!") end y=x endfunction
In this case, we suggest to use instead the calling
[flag,errmsg] = assert_checktrue ( condition ),
which simplifies the processing of the error.
function y=myfunction2(x) [flag,errmsg] = assert_checktrue ( x==12 ) if ( ~flag ) then error("Oups!") end y=x endfunction
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