Hello;
I have the incomplete gamma function (IGF) which is:
Y = a * (t ** b) * exp (-c * t)
and a data like this:
id a b c
what I am looking for is to calculate P150 which is the sum of Yt from t=1 to t=150
using params a b and c and get this:
id a b c P150
is there a method, with SAS, which allows me to do this without using Excel (which I often do).
I always found help in this forum. Thank you in advance.
Time to upgrade! Once a function is defined with FCMP, it can be used in great many places, including, for example, in SQL
data myData;
input id :$12. a b c;
datalines;
T0600021251 16.79361 0.04351 0.00253
T2100050954 10.62616 0.24511 0.00231
T2100071545 12.54940 0.21685 0.00301
T2300051246 15.35562 0.15303 0.00306
T2300051372 21.58488 0.05164 0.00168
T2300051449 24.43391 0.00001 0.00269
T2300051462 14.47446 0.18741 0.00365
T2300051496 32.75656 0.00001 0.00236
T2300051533 19.42636 0.00001 0.00212
T2300051540 20.75340 0.04351 0.00229
T2300051622 8.27472 0.25447 0.00237
T2300051655 7.73511 0.31439 0.00418
T2300051846 8.87238 0.26569 0.00306
T2300051849 26.85240 0.00001 0.00127
T2300056142 10.45094 0.32418 0.00475
T2300057352 22.15670 0.03133 0.00310
T2300058009 15.46157 0.12580 0.00212
;
proc fcmp outlib=sasuser.fcmp.math;
function P150(a, b, c);
do t = 1 to 150;
r + a * (t ** b) * exp (-c * t);
end;
return (r);
endsub;
run;
options cmplib=sasuser.fcmp;
proc sql;
select *, P150(a, b, c) as d
from myData;
quit;
id a b c d T0600021251 16.79361 0.04351 0.00253 2487.253 T2100050954 10.62616 0.24511 0.00231 3633.33 T2100071545 12.5494 0.21685 0.00301 3614.663 T2300051246 15.35562 0.15303 0.00306 3396.119 T2300051372 21.58488 0.05164 0.00168 3514.853 T2300051449 24.43391 0.00001 0.00269 3011.899 T2300051462 14.47446 0.18741 0.00365 3520.605 T2300051496 32.75656 0.00001 0.00236 4133.227 T2300051533 19.42636 0.00001 0.00212 2493.532 T2300051540 20.7534 0.04351 0.00229 3127.748 T2300051622 8.27472 0.25447 0.00237 2927.307 T2300051655 7.73511 0.31439 0.00418 3039.666 T2300051846 8.87238 0.26569 0.00306 3113.042 T2300051849 26.8524 0.00001 0.00127 3665.269 T2300056142 10.45094 0.32418 0.00475 4090.179 T2300057352 22.1567 0.03133 0.0031 3001.778 T2300058009 15.46157 0.1258 0.00212 3287.251
Assuming the sum is over integer values of t :
proc fcmp outlib=sasuser.fcmp.math;
function P150(a, b, c);
do t = 1 to 150;
r + a * (t ** b) * exp (-c * t);
end;
return (r);
endsub;
run;
options cmplib=sasuser.fcmp;
data _null_;
a = 1; b = 2; c = 3;
y = P150(a, b, c);
put _all_;
run;
Thank you for your reponce PG,
Sorry, I think that the SAS version that I have (9.0) does not include the procedure FCMP
and Second, you set the values of a, b and c where as in my data file these values change from one line to another.
this is how my file looks:
id | a | b | c |
T0600021251 | 16.79361 | 0.04351 | 0.00253 |
T2100050954 | 10.62616 | 0.24511 | 0.00231 |
T2100071545 | 12.54940 | 0.21685 | 0.00301 |
T2300051246 | 15.35562 | 0.15303 | 0.00306 |
T2300051372 | 21.58488 | 0.05164 | 0.00168 |
T2300051449 | 24.43391 | 0.00001 | 0.00269 |
T2300051462 | 14.47446 | 0.18741 | 0.00365 |
T2300051496 | 32.75656 | 0.00001 | 0.00236 |
T2300051533 | 19.42636 | 0.00001 | 0.00212 |
T2300051540 | 20.75340 | 0.04351 | 0.00229 |
T2300051622 | 8.27472 | 0.25447 | 0.00237 |
T2300051655 | 7.73511 | 0.31439 | 0.00418 |
T2300051846 | 8.87238 | 0.26569 | 0.00306 |
T2300051849 | 26.85240 | 0.00001 | 0.00127 |
T2300056142 | 10.45094 | 0.32418 | 0.00475 |
T2300057352 | 22.15670 | 0.03133 | 0.00310 |
T2300058009 | 15.46157 | 0.12580 | 0.00212 |
… |
30588 different id.
Time to upgrade! Once a function is defined with FCMP, it can be used in great many places, including, for example, in SQL
data myData;
input id :$12. a b c;
datalines;
T0600021251 16.79361 0.04351 0.00253
T2100050954 10.62616 0.24511 0.00231
T2100071545 12.54940 0.21685 0.00301
T2300051246 15.35562 0.15303 0.00306
T2300051372 21.58488 0.05164 0.00168
T2300051449 24.43391 0.00001 0.00269
T2300051462 14.47446 0.18741 0.00365
T2300051496 32.75656 0.00001 0.00236
T2300051533 19.42636 0.00001 0.00212
T2300051540 20.75340 0.04351 0.00229
T2300051622 8.27472 0.25447 0.00237
T2300051655 7.73511 0.31439 0.00418
T2300051846 8.87238 0.26569 0.00306
T2300051849 26.85240 0.00001 0.00127
T2300056142 10.45094 0.32418 0.00475
T2300057352 22.15670 0.03133 0.00310
T2300058009 15.46157 0.12580 0.00212
;
proc fcmp outlib=sasuser.fcmp.math;
function P150(a, b, c);
do t = 1 to 150;
r + a * (t ** b) * exp (-c * t);
end;
return (r);
endsub;
run;
options cmplib=sasuser.fcmp;
proc sql;
select *, P150(a, b, c) as d
from myData;
quit;
id a b c d T0600021251 16.79361 0.04351 0.00253 2487.253 T2100050954 10.62616 0.24511 0.00231 3633.33 T2100071545 12.5494 0.21685 0.00301 3614.663 T2300051246 15.35562 0.15303 0.00306 3396.119 T2300051372 21.58488 0.05164 0.00168 3514.853 T2300051449 24.43391 0.00001 0.00269 3011.899 T2300051462 14.47446 0.18741 0.00365 3520.605 T2300051496 32.75656 0.00001 0.00236 4133.227 T2300051533 19.42636 0.00001 0.00212 2493.532 T2300051540 20.7534 0.04351 0.00229 3127.748 T2300051622 8.27472 0.25447 0.00237 2927.307 T2300051655 7.73511 0.31439 0.00418 3039.666 T2300051846 8.87238 0.26569 0.00306 3113.042 T2300051849 26.8524 0.00001 0.00127 3665.269 T2300056142 10.45094 0.32418 0.00475 4090.179 T2300057352 22.1567 0.03133 0.0031 3001.778 T2300058009 15.46157 0.1258 0.00212 3287.251
Yes PG Stats, sure, I should do it , when strong people like you offered me some great solutions to my problems. thank you so much. Just an explanation, for people who are interested to my question; This solution is interesting for the calculation of the cumulative amount that changes with time. in my case I use it to calculate the amount of milk production at different date using the wood or Wilmink function.
thank you again PG stats, and good luck readers.
@soumri: Thanks for pointing out the application area.
If you don't have PROC FCMP at your disposal (yet), you can simply copy the DO loop from PG's PROC FCMP step into his data step after the INPUT statement and an additional assignment statement r=0; (to initialize variable r, which is automatically retained due to the sum statement).
@FreelanceReinhard Yes, it's true, it works correctly. thank you very much very nice to participate.
data want;set have;
r=0;
do t = 1 to 150;
r + al * (t ** bl) * exp (-cl * t);
end;
run;
it's ok
Hello PGStats;
do you explain me please the utility of using a proc fcmp, while the concept proposed by @FreelanceReinhard renders results numerically equal.
What is the difference.
Thank you for your help.
I think, PG has already mentioned the key benefit of the FCMP approach when he wrote: "Once a function is defined with FCMP, it can be used in great many places, including, for example, in SQL".
Indeed, you can call the function, across programs, in a data step without copying or remembering the formula and without the risk of name conflicts between variables used in the function definition and other data step variables. Moreover, you can call it in places where it would be impossible to paste the defining SAS code, e.g. in WHERE conditions (in both DATA and PROC steps as well as dataset options), nested with other functions, in a macro context (via %SYSFUNC), a format definition (with SAS 9.3 or higher) or in PROC SQL, as has been demonstrated.
The numerical results are equal to those from the data step DO loop.
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