I’m sorry to say that I haven’t used very many of the advanced functions. The “Free42” RPN calculator is easy to use & works well. (Also, the approximately $90 or so purchase price at the time, with a young family really hurt!)Īlthough, my present position for the last twenty years doesn’t require anything advanced, RPN is still my first choice for a calculator. I used it very extensively, writing time saving programs for my job. I first started with my first RPN calculator when I worked in electrical engineering in the eighties with my HP15C. But I certainly can’t trust any results this app produces. I am completely baffled as to how this can be happening. At various times the Solver has worked correctly returned the ‘Sign Reversal’ error message found 7 as a root found only the root x=1 regardless of the initial estimate and found 6.03125 as a root. I have been using the quadratic equation x^2-5x+4 as a test case. But the Solver keeps producing strange, unexplainable results. I offer my apologies for my part in the confusion but not on behalf of some terribly confusing third party documentation. A little serious thinking took care of the rest. Referring to some high-quality (HP and true PDF, not scanned images) documentation cleared up some confusion about programming. Hp33s cannot handle this directly depend miss of handling square root with complex value (but working with work around y^x, ie y^0.5) and cannot handle and store complex value in store registers - hp33s is hard to work with complex values IMHO.Update: Developer’s comment that Solver uses TWO initial estimates cleared up some of the mystery. and need bigger caculator like hp48 and better or TI 86 and better (possible TI 83?) to find same functionality. Hp42s is very useful to handle 'simple' but complex valued formula as aboveĪnd can also handle complex matrices and matrice operation like eigenvectorĪnd cross products etc. OK, this can easly solve on Mathematica or Mathcad, but for 'quick an dirty - thinking' calc, hp42s or simular calculator with complex support is very useful. fraction of 'r + jwl' / 'g + jwc', result in complex valueĪnd answer impedances Z in complex value.Īnd present answer on display in result resistance value and angle now, stack has 'r + jwl' value on Y and 'g + jwc' value on X positions * calculate for 'wl' and have now value 'r' and 'wl' on stackĢnd complex make complex value 'r + jwl'Ģnd complex make complex value 'g + jwc' STO 00 copy and store 'w' value to later using Ok, calculate equation 'sqr( (r+jwl)/(g + jwc) )': Select 'REGS' in dispaly make all store registe to handle complex numbers now and need this moment only one time (to next machine reset) OK, first make, first time installed/started free42 calculator to store complex values in registers:Ģnd modes -> select RECT make view and input to reqtangular modeĢnd complex make this zero to complex zero I using hp42s on many year and now finding free GPL software versionĪnd show her input example for this calculator on equation 'sqr( (r+jwl)/(g + jwc) )': With full 'telegraph equation' in all situation for more accurate value Paper and pencil, but if using complex capable calculator is it easy to handle Simplified formula for low and high frequecy is maked to calculate with If working in range 20 KHz to 2 MHz on cable, is tricky part make simplified equations like above and need calculate with whole 'telegraph equation' to estimate cable character on actual frequency - And in old transsissions theory books marks this part is not intresting depend of more complicate math for students - but if works with ADSL, RS-485 etc. This effect is not included in simplified formula above or full telegraph equation. Impedances is are real and attenuate depends of 'r' and 'g' and more or less same for all frequency, but give slowly higher attenuate of frequency depend increase of skin effect of conduct and dielecric loss of insulator between cords. Simplified calculation for high frequencys > 200 KHz on cableĪlpha = (r/2 * sqr(c/l)) + (g/2 * sqr(l/c)) Neper Simplified equation to calculate for low fequency 0 - 20 KHz on cable:Ĭurrent is 45 degree phaseshift before voltageĪnd result high frequency attenuate more than low frequency J => j^2 = -1, imaginary number, normaly 'i' but here in 'j' Measure inductanse on shorted piece of cableĪnd measure capacitance opened same piece of cableįor low frequences ( 0-20 kHz) is also interest of resistanse of shorted pieces of cablesĪnd for high frequency is loss tangent of insulation of cables and convert to 'g'
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