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+--- Thread: sum and product inside a program (/thread-5956.html)
sum and product inside a program - Helge Gabert - 03-29-2016 09:52 PM
I got strange results in one of my programs and it appears that sum() and product() don't work correctly, if called inside a program.
Example:
POLY(n,z)
BEGIN
LOCAL k;
sum(z^k/k^n, 1, 3, 1);
END;
returns +inf for POLY(2,.1).
But in CAS, from the command line, sum(0.1^k/k^2), returns .1026 . . .
Similar problem with product inside a program.
RE: sum and product inside a program - roadrunner - 03-29-2016 11:57 PM
I could never get sum() to work right inside a program unless I made it a CAS program. This seems to do what you need:
#cas
POLY(n,z):=
BEGIN
LOCAL k;
sum(z^k/k^n,k,1,3,1);
END;
#end
-road
RE: sum and product inside a program - Helge Gabert - 03-30-2016 12:43 AM
Thanks! I'll try that.
RE: sum and product inside a program - Bill_McDonough - 05-22-2017 11:04 PM
Per Cyrille:
sum is sum(expr, var, reals...)... this program is missing an EXPORT and a k in the sum to work.
EXPORT POLY(n,z)
BEGIN
LOCAL k;
sum(z^k/k^n, k, 1, 3, 1);
END;
RE: sum and product inside a program - Helge Gabert - 05-24-2017 01:53 PM
Yes, thanks for pointing this out - - I noticed that I forgot the index variable k as soon as I started on the CAS version a while back. All is well.