Using the C Math Library

Avoiding Memory Leaks in Your Functions

Follow these recommendations to avoid the memory leaks.

1. Never call a library function without assigning the array it returns to an array variable (by calling mlfAssign()) or without embedding the call as an argument to a library function.

Memory leak:

mlfSin(X);

The array returned by mlfSin() is not bound to a variable and never freed.

2. Never assign a value to an array variable without subsequently deleting the array.

Memory leak:

void func(mxArray *y)
{
mxArray *x;

mlfEnterNewContext(0,1,y);
mlfAssign(&x, mlfSin(y));
mlfRestorePreviousContext(0,1,y);
}

You must pair each mxArray* declaration with a call to mxDestroyArray().

3. Never use the assignment operator to assign array values.

Unexpected termination of your program:

x is a temporary array. If x is subsequently passed as an input argument to a function, that function will delete x.Any subsequent reference to x will cause your program to crash.

x = mlfSin(y);                   /* x is temporary. */
a = mlfPlus(x, mlfScalar(1));    /* x is deleted. */
b = mlfPlus(a, x);               /* Program crashes. */

Automated Memory Management

Using Automated Memory Management