///---------------------------------------------------------------------------------
///
///---------------------------------------------------------------------------------
StateVector3D SmokeUpdateStrategy::RK4( const StateVector3D& initialState, const double& deltaT )
{
StateVector3D s1 = initialState;
StateVector3D s1Derivative = CalculateDerivative( s1 );
StateVector3D s2 = initialState + s1Derivative * (float)(deltaT / 2.0);
StateVector3D s2Derivative = CalculateDerivative( s2 );
StateVector3D s3 = initialState + s2Derivative * (float)(deltaT / 2.0);
StateVector3D s3Derivative = CalculateDerivative( s3 );
StateVector3D s4 = initialState + s3Derivative * (float)deltaT;
StateVector3D s4Derivative = CalculateDerivative( s4 );
StateVector3D nextState = initialState + (s1Derivative + (s2Derivative * 2.0f) + (s3Derivative * 2.0f) + s4Derivative) * (float)(deltaT / 6.0);
return nextState;
}
/*
* The overall architecture is to repeat the same process,
* terminating only if a negative degree is entered.
*
* Thus, we repeat the process READ->COMPUTE->PRINT.
*
*/
int main(void)
{
int maxDegree; /* the maximum degree of the polynomial the user wants to enter */
int *polynomial = NULL; /* the polynomial is represented by its coefficients, stored here */
int *derivative = NULL; /* the reciprocal polynomial is represented by the coefficients stored here */
while (1) {
/*
* Clear the data structures from previous iteration
* NB It's safe to free a NULL pointer
*/
free(polynomial);
free(derivative);
polynomial = derivative = NULL;
/*
* Read data
*/
printf("Please enter the maximum degree of the polynomial: ");
scanf("%d", &maxDegree);
// SENTINEL: Quit program if user inputs negative degree
if (maxDegree < 0) break;
/*
* Allocate memory
*/
polynomial = calloc(maxDegree+1, sizeof(int) );
derivative = calloc(maxDegree, sizeof(int) );
if (!polynomial || !derivative) {
fprintf(stderr, "Error: unable to allocate memory.\n");
exit(EXIT_FAILURE);
}
printf("Please enter the coefficients: ");
ReadPolynomial(polynomial, maxDegree);
/*
* Compute the derivative
*/
CalculateDerivative(polynomial, derivative, maxDegree);
/*
* Print the result
*/
PrintPolynomial("The polynomial is", polynomial, maxDegree);
PrintPolynomial("Its derivative is", derivative, maxDegree);
printf("\n");
}
return 0;
}
