## Laguerre RSI

Laguerre RSI (LRSI) was authored by John Ehlers in his article Time Warp – Without Space Travel. The Relative Strength Index (RSI) itself, was authored by Wells Wilder. The LRSI uses the current price, a user defined gamma factor and plenty of feedback to calculate its final value. The user may change the input (close) and the gamma factor. This indicator’s definition is further expressed in the condensed code given in the calculation below. ### How To Trade Using the Laguerre RSI

The Laguerre RSI may be used in conjunction with other studies. No trading signals are calculated.

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Go to the top menu, choose Study>John Ehlers>Laguerre RSI

or go to the top menu, choose Add Study, start typing in this study name until you see it appear in the list, click on the study name, click OK.

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### Calculation

//input = price, user defined, default is close
//gamma = user defined factor, default is 0.5
//prev = previous, index = current bar number

```prevL0 = ifNull(price, lo[index-1]);  //feedback ingredent
prevL1 = ifNull(price, l1[index-1]);  //feedback ingredent
prevL2 = ifNull(price, l2[index-1]);  //feedback ingredent
prevL3 = ifNull(price, l3[index-1]);  //feedback ingredent

l0 = (1 - gamma) * price + gamma * prevL0;
l1 = -gamma *l0 + prevL0 + gamma * prevL1;
l2 = -gamma * l1 + prevL1 + gamma * prevL2;
l3 = -gamma * l2 + prevL2 + gamma * prevL3;

if(l0 moreOrEqual l1) cu = l0 - l1;
else cd = l1 - l0;

if(l1 moreOrEqual l2) cu = cu + l1 - l2;
else cd = cd + rl2 - l1;

if(l2 moreOrEqual l3) cu = cu + l2 - l3;
else cd = cd + l3 - l2;

if ( cu + cd notEqual 0.0) rsi = cu / (cu + cd);
plot rsi;```