// **************************************************************
fdouble gammp(fdouble a, fdouble x)
/**
* Returns the incomplete gamma function P (a, x).
* See "Numerical Recipes in C", 2nd edition, page 218
*/
{
fdouble gamser, gammcf, gln;
if (x < 0.0 || a <= 0.0)
{
std_cout << "Invalid arguments in routine gammp\n";
abort();
}
if (x < (a+fone))
{
//Use the series representation.
gser(&gamser, a, x, &gln);
return gamser;
} else {
// Use the continued fraction representation and take its complement.
gcf(&gammcf, a, x, &gln);
return fone - gammcf;
}
}
int main(void)
{
char txt[MAXSTR];
int i,nval;
float a,gamser,gln,val,x;
FILE *fp;
if ((fp = fopen("fncval.dat","r")) == NULL)
nrerror("Data file fncval.dat not found\n");
fgets(txt,MAXSTR,fp);
while (strncmp(txt,"Incomplete Gamma Function",25)) {
fgets(txt,MAXSTR,fp);
if (feof(fp)) nrerror("Data not found in fncval.dat\n");
}
fscanf(fp,"%d %*s",&nval);
printf("\n%s\n",txt);
printf("%4s %11s %14s %14s %12s %8s\n","a","x",
"actual","gser(a,x)","gammln(a)","gln");
for (i=1; i<=nval; i++) {
fscanf(fp,"%f %f %f",&a,&x,&val);
gser(&gamser,a,x,&gln);
printf("%6.2f %12.6f %12.6f %12.6f %12.6f %12.6f\n",
a,x,val,gamser,gammln(a),gln);
}
fclose(fp);
return 0;
}
double
gammq(double a, double x)
{
if (x < a || a <= 0.0) {
if (a < 0) fprintf(stderr, "gammq(%f, %f): invalid arguments\n", a, x);
return 0.0;
}
if (x < a + 1.0) return 1.0 - gser(a, x);
return gcf(a, x);
}
/**
Represents incomplete error function, P(a,x)
**/
float gammp(float a, float x) {
float gamser,gammcf,gln;
if(x < 0.0 || a <= 0.0) printf("Invalid arguments in routine gammp");
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return gamser;
} else {
gcf(&gammcf,a,x,&gln);
return 1.0 - gammcf;
}
}
double gammq(double a, double x)
{
if(x < 0.0 || a <= 0.0)
printf("bad args in gammq\n");
if(x == 0.0)
return 1.0;
else if((int) a >= ASWITCH)
return gammpapprox(a, x, 0);
else if(x < a + 1.0)
return 1.0 - gser(a, x);
else
return gcf(a, x);
}
double gammq ( double a, double x )
{
double gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0) nrerror("Invalid arguments in routine GAMMQ");
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return 1.0-gamser;
} else {
gcf(&gammcf,a,x,&gln);
return gammcf;
}
}
double numrec_gammp(double a, double x)
{
double gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0) my_error("Invalid arguments in routine gammp");
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return gamser;
} else {
gcf(&gammcf,a,x,&gln);
return 1.0-gammcf;
}
}
float gammp(float a, float x)
{
if(x < 0.0 || a <= 0.0)
printf("bad args in gammp\n");
if(x == 0.0)
return 0.0;
else if((int) a >= ASWITCH)
return gammpapprox(a, x, 1);
else if(x < a + 1.0)
return gser(a, x);
else
return 1.0 - gcf(a, x);
}
double gammaq(double a, double x)
{
double gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0) return 0;
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return 1.0-gamser;
} else {
gcf(&gammcf,a,x,&gln);
return gammcf;
}
}
double Statistics::gammq(double a, double x)
{
double gamser, gammcf, gln, pval;
if(x < (a + 1.0)){
gser(&gamser, a, x, &gln);
pval = 1.0 - gamser;
}
else{
gcf(&gammcf, a, x, &gln);
pval = gammcf;
}
return pval;
}
DP NR::gammp(const DP a, const DP x)
{
DP gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0)
nrerror("Invalid arguments in routine gammp");
if (x < a+1.0) {
gser(gamser,a,x,gln);
return gamser;
} else {
gcf(gammcf,a,x,gln);
return 1.0-gammcf;
}
}
// compute incomplete gamma function
double gammp(const double a, const double x)
{
if (x < 0 || a < 0)
{
return -1;
}
double chi;
if (x < (a + 1.0))
chi = 1.0 - gser(a, x);
else
chi = gcf(a, x);
return chi;
}
void gammp (double *a, double *x, double *res)
{
if (*x < 0.0 || *a <= 0.0)
{ output("Invalid arguments in routine gammp\n");
error=1; return;
}
if (*x < (*a+1.0)) {
*res=gser(*a,*x);
return;
} else {
*res=gamm(*a)-gcf(*a,*x);
return;
}
}
Scalar gammq(Scalar a, Scalar x)
{
Scalar gamser,gammcf,gln;
// void gcf(),gser(),nrerror();
// if (x < 0.0 || a <= 0.0) nrerror("Invalid arguments in routine GAMMQ");
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return 1.0-gamser;
} else {
gcf(&gammcf,a,x,&gln);
return gammcf;
}
}
/**
* Returns the incomplete gamma function P(a,x)
*
* "Numerical Recipes in C", Section 6.2
*/
double gammap( const double x, const double a )
{
double gam,gln;
if (x < 0.0 || a <= 0.0){
printf("Incomplete Gamma Calculated with: x:%f and a:%f\n",x,a);
failwith("Invalid argument for incomplete gamma");
}
if ( x < (a+1.0)) {
gser(&gam,a,x,&gln);
} else {
gcf (&gam,a,x,&gln); //inverse of continued fraction representation
gam = 1.0 - gam;
}
return gam;
}
double gammq(double a, double x)
{
void gcf(double *gammcf, double a, double x, double *gln);
void gser(double *gamser, double a, double x, double *gln);
double gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0) my_error("Invalid arguments in routine gammq");
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return 1.0-gamser;
} else {
gcf(&gammcf,a,x,&gln);
return gammcf;
}
}
double gammaCDF(double a, double x) {
double gln, p;
if (x <= 0.0 || a <= 0.0)
return 0.0;
else if (a > LARGE_A)
return gnorm(a, x);
else {
gln = lngamma(a);
if (x < (a + 1.0))
return gser(a, x, gln);
else
return (1.0 - gcf(a, x, gln));
}
}
double gammq ( double a, double x )
{
double gammser, gammcf, gln;
if (x < 0.0 || a <= 0.0) error("Invalid arguments in routine gammq");
if (x < (a + 1.0))
{
gser (&gammser, a, x, &gln); // use the series representation
return (1.0 - gammser); // and take its complement
}
else
{
gcf ( &gammcf, a, x, &gln); // use the continued fraction representation
return gammcf;
}
}
//gammq ---- returns the incomplete gamma function Q(a,x) = 1 - P(a,x).
float Test::gammq(float a, float x) {
float gamser, gammcf, gln;
//cout <<"a " << a<< " x "<<x<<endl;
if (x < 0.0 || a <= 0.0) {
nerror("Invalid arguments in routine gammq");
}
if (x < (a + 1.0)) { //use the series representation
gser(&gamser, a, x, &gln);
return 1.0 - gamser; //and take its complement
}
else {
gcf(&gammcf, a, x, &gln); //use the continued fraction representation
return gammcf;
}
}
// Function: gammq(a,x)
//
REAL_TYPE gammq(REAL_TYPE a, REAL_TYPE x)
{
REAL_TYPE gamser, gammcf, gln;
if((x<0.0||a<=0.0)) throw(std::invalid_argument(std::string("gammp():x must be >= 0 and a must be > 0")));
if(x<(a+1.0))
{
gser(&gamser,a,x,&gln);
return 1.0-gamser;
}
else
{
gcf(&gammcf,a,x,&gln);
return gammcf;
}
}
float gammq(float a, float x)
{
void gcf(float *gammcf, float a, float x, float *gln);
void gser(float *gamser, float a, float x, float *gln);
void nrerror(char error_text[]);
float gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0) nrerror("Invalid arguments in routine gammq");
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return 1.0-gamser;
} else {
gcf(&gammcf,a,x,&gln);
return gammcf;
}
}
double gammp(double a, double x) // Returns normalised lower incomplete gamma function
{
void gcf(double *gammcf,double a, double x, double *gln);
void gser(double *gamser, double a, double x, double *gln);
double gamser,gammcf,gln;
if(x<0) DEBUG << "Error: Argument of incomplete gamma function <= 0" << endl;
if(x< (a+1.0E0))
{
gser(&gamser,a,x,&gln);
return gamser;
}
else{
gcf(&gammcf, a, x, &gln);
return (1.0E0-gammcf);
}
}
REAL_TYPE gammp(REAL_TYPE a, REAL_TYPE x)
{
REAL_TYPE gamser, gammcf, gln;
assert(!(x<0.0||a<=0.0)); // Invalid arguments
if(x<(a+1.0))
{
gser(&gamser,a,x,&gln);
return gamser;
}
else
{
gcf(&gammcf,a,x,&gln);
return 1.0-gammcf;
}
}
double gammp(double a, double x)
{
/* void gcf(double *gammcf, double a, double x, double *gln);
void gser(double *gamser, double a, double x, double *gln);
void nrerror(char error_text[]); */
double gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0) nrerror("Invalid arguments in routine gammp");
if (x < (a+1.0)) {
gser(&gamser,a,x,&gln);
return gamser;
} else {
gcf(&gammcf,a,x,&gln);
return 1.0-gammcf;
}
}
//Returns the incomplete gamma function P (a, x).
double gammp(double a, double x)
{
int gcf(double *gammcf, double a, double x, double *gln);
int gser(double *gamser, double a, double x, double *gln);
double gamser,gammcf,gln;
if (x < 0.0 || a <= 0.0) {
fprintf (stderr, "Invalid arguments in routine gammp (x=%5.1lf, a=%5.1lf).\n", x, a);
exit (1);
}
if (x < (a+1.0)) { // Use the series representation.
gser(&gamser,a,x,&gln);
return gamser;
} else { // Use the continued fraction representation
gcf(&gammcf,a,x,&gln);
return 1.0-gammcf; //and take its complement.
}
}
double
vpRobust::gammp(double a, double x)
{
double gamser=0.,gammcf=0.,gln;
if (x < 0.0 || a <= 0.0)
std::cout << "Invalid arguments in routine GAMMP";
if (x < (a+1.0))
{
gser(&gamser,a,x,&gln);
return gamser;
}
else
{
gcf(&gammcf,a,x,&gln);
return 1.0-gammcf;
}
}
double gammp(const double a, double x) {
static const int ASWITCH = 100;
if(x < 0.0 || a <= 0.0) {
std::cout << "Bad value in Fgamma!";
return 0.0;
}
if(x == 0.0) {
return 0.0;
} else if(a >= ASWITCH) {
return gammpapprox(a,x,1); /* use quadrature */
} else if(x < a + 1.0) {
return gser(a,x); /* use the series expansion */
} else {
return 1.0 - gcf(a,x); /* use the continued fraction expansion */
}
}
double gammp( double a, double x )
{
// x = chisquare, a = df/2
if( x < 0.0 || a <= 0.0 )
{
printf( "error: invalid arguments in routine gammp" );
exit( 1 );
}
if( x < ( a + 1.0 ) )
{
gser( a, x );
return( gamser );
}
else
{
gcf( a, x );
return( 1.0 - gammcf );
}
// returns the incomplete gamma function P(a,x);
}
