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74 lines
2.6 KiB
Fortran
74 lines
2.6 KiB
Fortran
*DECK CPEVL
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SUBROUTINE CPEVL (N, M, A, Z, C, B, KBD)
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C***BEGIN PROLOGUE CPEVL
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C***SUBSIDIARY
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C***PURPOSE Subsidiary to CPZERO
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C***LIBRARY SLATEC
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C***TYPE SINGLE PRECISION (CPEVL-S)
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C***AUTHOR (UNKNOWN)
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C***DESCRIPTION
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C
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C Evaluate a complex polynomial and its derivatives.
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C Optionally compute error bounds for these values.
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C
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C INPUT...
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C N = Degree of the polynomial
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C M = Number of derivatives to be calculated,
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C M=0 evaluates only the function
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C M=1 evaluates the function and first derivative, etc.
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C if M .GT. N+1 function and all N derivatives will be
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C calculated.
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C A = Complex vector containing the N+1 coefficients of polynomial
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C A(I)= coefficient of Z**(N+1-I)
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C Z = Complex point at which the evaluation is to take place.
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C C = Array of 2(M+1) words into which values are placed.
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C B = Array of 2(M+1) words only needed if bounds are to be
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C calculated. It is not used otherwise.
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C KBD = A logical variable, e.g. .TRUE. or .FALSE. which is
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C to be set .TRUE. if bounds are to be computed.
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C
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C OUTPUT...
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C C = C(I+1) contains the complex value of the I-th
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C derivative at Z, I=0,...,M
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C B = B(I) contains the bounds on the real and imaginary parts
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C of C(I) if they were requested.
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C
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C***SEE ALSO CPZERO
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C***ROUTINES CALLED I1MACH
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C***REVISION HISTORY (YYMMDD)
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C 810223 DATE WRITTEN
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C 890531 Changed all specific intrinsics to generic. (WRB)
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C 890831 Modified array declarations. (WRB)
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C 891214 Prologue converted to Version 4.0 format. (BAB)
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C 900402 Added TYPE section. (WRB)
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C***END PROLOGUE CPEVL
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C
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COMPLEX A(*),C(*),Z,CI,CIM1,B(*),BI,BIM1,T,ZA,Q
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LOGICAL KBD
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SAVE D1
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DATA D1 /0.0/
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ZA(Q)=CMPLX(ABS(REAL(Q)),ABS(AIMAG(Q)))
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C***FIRST EXECUTABLE STATEMENT CPEVL
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IF (D1 .EQ. 0.0) D1 = REAL(I1MACH(10))**(1-I1MACH(11))
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NP1=N+1
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DO 1 J=1,NP1
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CI=0.0
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CIM1=A(J)
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BI=0.0
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BIM1=0.0
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MINI=MIN(M+1,N+2-J)
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DO 1 I=1,MINI
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IF(J .NE. 1) CI=C(I)
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IF(I .NE. 1) CIM1=C(I-1)
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C(I)=CIM1+Z*CI
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IF(.NOT. KBD) GO TO 1
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IF(J .NE. 1) BI=B(I)
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IF(I .NE. 1) BIM1=B(I-1)
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T=BI+(3.*D1+4.*D1*D1)*ZA(CI)
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R=REAL(ZA(Z)*CMPLX(REAL(T),-AIMAG(T)))
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S=AIMAG(ZA(Z)*T)
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B(I)=(1.+8.*D1)*(BIM1+D1*ZA(CIM1)+CMPLX(R,S))
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IF(J .EQ. 1) B(I)=0.0
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1 CONTINUE
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RETURN
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END
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