This section describes the functions to control the program flow.

if

Description
If the condition is true, executes statements.
Used in FDTD and FDE.

Syntax
(1) If the expression is true, executes statements.

if expression
    statements
end

(2) If the expression is true, executes statements_1. Otherwise, execute statements_2.

if  expression
    statements_1
else
    statements_2
end

(3)If the expression_k is true, executes the statements_k.

if expression_1
    statements_1
elseif expression_2
    statements_2
...
elseif expression_k
    statements_k
else
    statements_k+1
end

Example

if  0
    'true-1'
elseif 0
    'true-2'
elseif 1
    'true-3'
else
    'else-part'
end 

Result:

val =
true-3

See also
while, for

while

Description
While the expression is true, executes the statement.
Used in FDTD and FDE.

Syntax
While the expression is true, executes the statement.

while expression
    statement;
end

Example

i = 0;
while i <= 5
    printf("i = %d\n", i);
    i = i + 1;
end

Result:

i = 1
i = 2
i = 3
i = 4
i = 5

See also
if, for

for

Description
Executes the statements for each element that meets the requirement.
Used in FDTD and FDE.

Syntax

for element = values
    statements;
end

Example

x = ["a", "sample", "string"];
for i = x
    printf ("%s ", i); 
end

Result:

a sample string 

See also
if, while

break

Description
Breaks the for or while loop, the code after break sentence will not be execute.
Used in FDTD and FDE.

Syntax
Breaks the for or while loop.

break;

Example

for  i = 1:100
    
    if i == 3 
        break;
    end
    printf("i = %d\n", i);
end

Result:

i = 1
i = 2

See also
continue

continue

Description
Terminates the current iteration and starts the next iteration of for or while loop.
Used in FDTD and FDE.

Syntax
The continue statement forces execution of the next iteration of the inner-most for or while loop to begin immediately.

continue;

Example

for  i = 1:4
    
    if i == 2
        continue;
    end
    printf("i = %d\n", i);
end

Result:

i = 1
i = 3
i = 4

See also
break

try, catch

Description
Executes statements and catches resulting errors.
Used in FDTD and FDE.

Syntax

Runs the block of commands. If an error occurs, the error message is not displayed and the script continues.

try 
    commands;

end
...

Runs the block of commands commands_1. If an error occurs, the error message is stored in the variable "error_message" and program control goes immediately to the catch block.

try
    commands_1;

catch error_message

    commands_2;

end

Example

Example 1:

# test code:
try
  a
catch exception
  D=4;
end

exception # show exception

Result:

exception =
'a' is undefined function or variable

Example 2:

# test code:
try
    'before error'
    a
    'after error'
end

Result:

val =
before error