I got the error of incorrect argument data type or missing argument in call to function 'gamma'.

function z=dist(x,rd,gm)
arguments
    x (1,:) {mustBeInteger}
    rd (1,:) {mustBePositive}
    gm (1,:) {mustBePositive}
    z=  (rd.^x)*gamma(gm)./gamma(gm+x).*(hypergeom(1+x,gm+x,-rd));
end

function a = rdist(n,rd,gm)
u=rand(1,n);
x=int16(n);
for i=1:n
    a=dist(x(i),rd(i),gm(i));
    while a(i)<u(i)
        x(i)=x(i)+1;
        a=a+dist(x(i),rd(i),gm(i));
    end
end

[KSSV]

Is the given code working?

[Kee Wah Fo]

No working. Appear "Check for incorrect argument data type or missing argument in call to function 'gamma'

Answer 1

[Steven Lord]

The gamma function in MATLAB requires its input to be a floating-point number, specifically the input must be "Data Types: single | double"

answer = gamma(5)

answer = 24

If you try to call it on with a value of an integer type as input, you'll receive an error. The result of adding a double and an integer is of the integer type, as you can see by looking at the information for the result variable in the output of whos below.

d = 5;
in = int8(1);
result = d + in;
whos d in result

  Name        Size            Bytes  Class     Attributes

  d           1x1                 8  double              
  in          1x1                 1  int8                
  result      1x1                 1  int8                

Calling double on result and calling gamma on that converted value will work, but calling gamma on result itself will not.

gamma(double(result))

ans = 120

gamma(result) % Will error

Check for incorrect argument data type or missing argument in call to function 'gamma'.

How is this relevant to your function? x must be of an integer type, so gm+x must be of that same integer type, and you try computing gamma(gm+x) in your code.

[Kee Wah Fo]

x is integer, a discrete number of a probability distribution. But gm is a positive number. Isn't my code error?

>> gm=1.2;

>> x=2;

>> gamma(gm+x)

ans = 2.4240

I am trying to generated a random data from a new distribution, due to new distribution is not include in Mathlab. Is that have other methods to do? Thank you.