Scilab绘图报错：未定义操作及函数重载问题求助

First, let's decode that French error message to get to the root of the problem:

Opération indéfinie pour les opérandes données. vérifier ou définir la fonction %b_1_s pour la surcharge。
Translation: "Undefined operation for the given operands. Check or define the %b_1_s function for overloading."

This error almost always boils down to a type mismatch in your operations—you're trying to run an operation (like subtraction, negation, etc.) between a boolean value (%t/%f) and another data type that Scilab doesn't support by default for that operation. The %b_1_s part tells us it's related to a unary operation (the _1_ component) involving a boolean (b) and some type s (could be a string, custom object, or even a variable that's overriding a built-in function).

Here's how to fix it step by step:

1. Locate the problematic line #

Check the error output for the line number where the crash occurs—this will point you directly to the operation causing the issue. Look for any math or logical operations involving boolean values.

2. Verify operand types #

Use Scilab's typeof() function to inspect the types of variables involved in the faulty operation. For example:

a = %t;
disp(typeof(a)); // Returns "boolean"
b = "sample text";
disp(typeof(b)); // Returns "string"
// Trying a - b would trigger your error

3. Convert incompatible types #

If you're mixing booleans with numeric values, convert the boolean to a number first using bool2s() (which maps %t to 1 and %f to 0):

// Bad: Direct operation on boolean and number
bool_var = %t;
result = bool_var - 5; // Triggers error

// Good: Convert boolean to numeric first
bool_var = %t;
numeric_bool = bool2s(bool_var);
result = numeric_bool - 5; // Returns -4, no error

4. Check for variable-name conflicts #

Sometimes you might accidentally overwrite a built-in Scilab function or type alias with a variable. For example, if you define s = 10; somewhere in your code, it could interfere with operations that expect s to refer to a specific type or function. Double-check your variable names to avoid clashes.

5. Overload the operator (for custom objects) #

If you're working with a custom object type you created, Scilab doesn't know how to handle operations between it and booleans by default. You'll need to define the %b_1_s function to overload the specific unary operation. For example, if s is your custom type, create a function like:

function out = %b_1_s(in)
    // Define how to handle the unary operation between boolean and your s type
    out = ...; // Implement your custom logic here
endfunction

内容的提问来源于stack exchange，提问作者Mohamed El Hadi