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From |
Nathan Danneman <ndanneman@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: passing optional arguments to functions in Mata |

Date |
Tue, 16 Jun 2009 15:14:10 -0400 |

Hi all, I have written a function for a part of a larger program. This program generates a numeric integral for a function that it calls. I would like to allow the outter function to pass several optional arguments (between zero and seven) on to the called function which is being integrated, which could then pass those arguments on to another lower-level function...etc. The code for the integration function is below. In the pasted example, I integrate the function named "trial" at bottom. As a very simple example, how could I get the overall function, NDint, to pass the z parameter on to "trial"? Thanks, Nathan //An n-slice integration routine using simpson's approximation mata mata clear mata set matalnum off scalar NDint( // to perform integration via simpson'sapproximation pointer(real scalar function) scalar f, //points to the functionto be integrated real scalar lower, //lower bound of integration real scalar higher, //upper bound real scalar m) // where m = number of slices, must be an EVEN number { if ( (m/2) != (floor(m/2)) ) _error("m must be an EVEN number") real scalar width //I like declarations, your mileage may vary real colvector Y real rowvector X real scalar n //slices plus one n = m+1 if (lower > higher) _error("limits of integration reversed") //make sure upper > lower NB: better to use _error() than return() width = (higher-lower) / m //calculates width of each "slice" Y = J(n,1,.) //creates an empty 15 x 1 column vector for (i=1; i<=n; i++) { x = lower + ((i-1)*width) Y[i,1] = (*f)(x) //places function evaluations directly into Y, avoiding all the copying you were doing previously } X = J(1,n,.) for (i=1;i<=n; i++) { if (i==1) X[1,i] = 1 if (i==n) X[1,i] = 1 if ((i/2) == (floor(i/2))) X[1,i] = 4 if ( ((i+1)/2) == (floor( ((i+1)/2)) ) & (i!=1) & (i!=n) ) X[1,i] = 2 } return(X*Y*width/3) //matrix multiplication makes this quicker and more readable } scalar trial(real scalar x) { //declares the output to be a scalar. otherwise you could run into problems in the main program return(z*exp(x)) } f = &trial() NDint(f, 0, 4, 60) end -- "Imagination is more important than knowledge..." -- Albert Einstein * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: passing optional arguments to functions in Mata***From:*Stas Kolenikov <skolenik@gmail.com>

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