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Hi, I wish to loop through the YR formula, in pic below, for values of z being 0,0.2,0.4,0.6,0.8,1.0,1.2,1.4,1.589. My progress so far is to produce an array evenly spaced z values and if the 1.0001 factor is not applied to hc_full then the last element of the z array is 1.362, rather than 1.589. It is obvious to me that I have some missing skill here, please throw me some hints. Regards, Tim
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Just define your 'x' vector of values, include in small loop. AtWill.sm (7kb) downloaded 42 time(s).
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Hi Jean, Thank you for the example file, I will study this for better understanding. I have longer arrays to create also so wish to automate; if I make z as in the pic or with equal spacing, is there a means of appending the final (1.589) value to the end of the array? Tim
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I do not see any problem.
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Originally Posted by: Tim Gowing I have longer arrays to create also so wish to automate; If you have longer array, equally spaced => as easy. Naturally, if not equally spaced, must be manual. AtWill.sm (14kb) downloaded 19 time(s).
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... if they are not equally spaced, but if there is a bit of logic in the spacing, we can select from a list that can be made/refactored as you wish at will from a little counter loop.
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Jean, Thank you for the counter loop example, this will stretch my programming comprehension. CBG, Thank you for typing the work from scratch, and showing no issue with the 1.589 value. I redefined hc_full immediately above the z range call and then the output changed to match your results. The hc_full is defined with an if statement. The 1.589 value is absent from the z range. The hc_full is redefined directly above the z range call (to override the value produced by the if statement) and the 1.589 value is now present in the z range. Have I contravened a working principle in some way? Tim
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Redefining hc_full using hc_full:=hc_full also fixes the z range array. Tim
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Originally Posted by: Tim Gowing Have I contravened a working principle in some way? Maybe not ? work sheet would help and no help. Smath 6179 does not take index on the RHS. hopper.sm (188kb) downloaded 16 time(s).
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for(3)-loops with initial, second and maximum value aren't robust if floating point values are specified. The internal representation of such numbers may differ from what is displayed due to round-off. Due to this it is not good programming style to test the equality of two floating point numbers without specifying a tolerance. If you want to be safe, you either introduce such a tolerance or you generate the list of values based on a list of integers. It should be possible to modify for(3) such that the tolerance is generated as a fraction of the difference between first and second value. loop.sm (5kb) downloaded 16 time(s).Edited by user 12 October 2017 23:47:12(UTC)
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True Martin: that damned floating point often creates a very small imaginary.
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In the context of this topic, there was an example in Mathcad 8. About solving an RK DE relative to "Orbit" by Steven Finch.
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